Terrorist groups come in many forms but have one thing in common: the use of violence to achieve their political objectives, whether those objectives are religious, ethnic, or ideological. In general, terrorist groups operate in a very local context, usually within a specific country or sub-region. Sometimes a terrorist group’s objectives extend beyond the internationally recognized borders of a state because their identity as a group transcends such legal or geographic boundaries.
Terrorist groups rarely pose a threat to the United States that rises to the threshold used by this Index: a substantial threat to the U.S. homeland; the ability to precipitate a war in a region of critical interest to the U.S.; and/or the ability to threaten the free movement of people, goods, or services through the global commons. Those that do meet these criteria are assessed in this section, with the exception of Hezbollah and other Iran-backed groups.1
Terrorist Threats to the Homeland from the Middle East and North Africa
Radical Islamist terrorism in its various forms remains a global threat to the safety of America’s citizens. Many terrorist groups operate in the Middle East, but those that are inspired by Islamist ideology also operate in Europe, Asia, and Africa.
The primary terrorist groups of concern to the U.S. homeland and to Americans abroad are the Islamic State of Iraq and al-Sham (ISIS) and al-Qaeda. Their threat is amplified when they can exploit areas with weak or nonexistent governance that allows them to plan, train, equip, and launch attacks.
Al-Qaeda and Its Affiliates. Al-Qaeda was founded in 1988 by Arab foreign fighters who flocked to Afghanistan to join the war against Soviet occupation of the country in the 1980s. With Osama bin Laden appointed emir, al-Qaeda was envisaged as a revolutionary vanguard that would radicalize and recruit Sunni Muslims across the world and lead a global Islamist revolution.2
After 9/11, al-Qaeda’s leadership fled Afghanistan. Much of the original cadre has now been killed or captured, including Osama bin Laden, and other key al-Qaeda leaders have been killed by targeted strikes in Afghanistan, Iraq, Pakistan, Syria, Yemen, and Somalia. However, al-Qaeda’s central leadership remains a potential threat to the U.S. homeland. Key elements of al-Qaeda’s leadership have survived or been replaced. Bin Laden’s successor as emir, Ayman al-Zawahiri, was forced deeper into seclusion and reportedly is sick or already dead from natural causes.3 Some al-Qaeda lieutenants are believed still to be in the Afghanistan–Pakistan region; others have taken refuge in Iran.4 Zawahiri’s likely successor, Mohammed Salahuddin Zeidan, reportedly also is based in Iran, where he operates under the nom de guerre Saif al-Adel (“Sword of Justice”).5
Like scores of other al-Qaeda members in Iran, Zeidan experienced imprisonment, some form of house arrest, and periods of relative freedom to operate inside Iran, depending on the state of relations between Iran and al-Qaeda. Although both share common enemies in the United States, Israel, and Sunni Arab regimes, they represent clashing Shia and Sunni Islamist ideologies and pursue conflicting long-term goals in Iraq, Lebanon, Syria, and Yemen.
Iran’s Islamic Revolutionary Guard Corps (IRGC) played an important role in establishing links with al-Qaeda in the early 1990s, when Bin Laden was based in Sudan. According to the report of the 9/11 Commission, the IRGC trained al-Qaeda members in camps in Lebanon and in Iran, where they learned to build much bigger bombs. The commission assessed that al-Qaeda may have assisted Iran-backed Saudi Hezbollah terrorists who executed the June 1996 bombing that killed 19 U.S. Air Force personnel at the Khobar Towers residential complex in Saudi Arabia and recommended that further investigation was needed to examine Iran’s ties to al-Qaeda.6
This long-neglected issue resurfaced in 2020 after The New York Times reported that al-Qaeda’s second-highest leader was killed in the heart of Iran’s capital city on August 7, 2020, by Israeli agents at the behest of the United States.7 The al-Qaeda leader, Abdullah Ahmed Abdullah, who went by the nom de guerre Abu Muhammad al-Masri, had been living in Iran at least since 2003 when he had fled from Afghanistan. Abdullah was a longtime fixture on the FBI’s “most wanted” list for his role in planning the August 7, 1998, bombings of the U.S. embassies in Kenya and Tanzania, which killed 224 people including 12 Americans. He was gunned down on a street in Tehran by two assassins on a motorcycle on the anniversary of that attack, which was al-Qaeda’s most lethal operation before 9/11.8
On January 12, 2021, then-Secretary of State Mike Pompeo confirmed the New York Times report about Abdullah’s death and warned that Iran had become the “new Afghanistan.”9 He also announced sanctions on two al-Qaeda leaders that continue to operate inside Iran.
Al-Qaeda also dispersed its fighters further afield, allowing for the development of regional affiliates that shared the long-term goals of al-Qaeda’s general command and largely remained loyal to it. These affiliates have enjoyed some success in exploiting local conflicts. In particular, the Arab Spring uprisings that began in 2011 enabled al-Qaeda to advance its revolutionary agenda, taking advantage of failed or failing states in Iraq, Libya, Mali, Syria, and Yemen. It is through these affiliates that al-Qaeda is able to project regional strength most effectively.
Yemen. Yemen has long been a bastion of support for militant Islamism. Yemenis made up a disproportionate number of the estimated 25,000 foreign Muslims that fought in the Afghan jihad against the Soviet Union in the 1980s. After that conflict ended, Yemen also attracted Westerners into the country to carry out terrorist operations there. In 1998, several British citizens were jailed for planning to bomb Western targets, including hotels and a church.10
Al-Qaeda’s first terrorist attack against Americans occurred in Yemen in December 1992 when a bomb was detonated in a hotel used by U.S. military personnel. In October 2000, in a much deadlier operation, it used a boat filled with explosives to attack the USS Cole in the port of Aden, killing 17 American sailors.11 The first U.S. drone strike outside Afghanistan after 9/11 also took place in Yemen, targeting those connected to the attack on the Cole.12
After 9/11 and following crackdowns in other countries, Yemen became increasingly important as a base of operations for al-Qaeda. In September 2008, al-Qaeda launched an attack on the U.S. embassy in Yemen that killed 19 people, including an American woman. Yemen’s importance to al-Qaeda increased further in January 2009 when al-Qaeda members who had been pushed out of Saudi Arabia merged with the Yemeni branch to form Al-Qaeda in the Arabian Peninsula (AQAP). This affiliate quickly emerged as one of the leading terrorist threats to the U.S. By 2010, CIA analysts assessed that AQAP posed a more urgent threat to U.S. security than the al-Qaeda general command based in Afghanistan/Pakistan.13
Much of this threat centered initially on AQAP’s Anwar al-Awlaki, a charismatic American-born Yemeni cleric who directed several terrorist attacks on U.S. targets before being killed in a drone air strike in September 2011. He had an operational role in the plot executed by Umar Farouk Abdulmutallab, the failed suicide bomber who sought to destroy an airliner bound for Detroit on Christmas Day 2009.14 Awlaki was also tied to plots to poison food and water supplies, as well as to launch ricin and cyanide attacks,15 and is suspected of playing a role in the November 2010 plot to dispatch parcel bombs to the U.S. in cargo planes. Additionally, Awlaki was in contact with Major Nidal Hassan, who perpetrated the 2009 Fort Hood shootings that killed 13 soldiers.16
Since Awlaki’s death, the number of AQAP-sanctioned external operations in the West has diminished.17 However, his videos on the Internet have continued to radicalize and recruit young Muslims, including the perpetrators of the April 2013 bombing of the Boston Marathon that killed three people.18
AQAP’s threat to Western security, while seemingly slightly reduced by Awlaki’s death, is still pronounced. Another attempt to carry out a bombing of Western aviation using explosives concealed in an operative’s underwear was thwarted by a U.S.–Saudi intelligence operation in May 2012.19 In August 2013, U.S. interception of al-Qaeda communications led to the closure of 19 U.S. embassies and consulates across the Middle East and Africa because of indications that AQAP was planning a massive attack.20 In January 2015, two AQAP-trained terrorists murdered staff members and nearby police at Charlie Hebdo magazine in Paris.21 In 2017, aviation was targeted once again by a plan to conceal bombs in laptop batteries.22
AQAP launched another successful attack inside the United States on December 6, 2019, when a radicalized Saudi Royal Air Force officer being trained at Naval Air Station Pensacola killed three U.S. Navy sailors and wounded eight other Americans in a shooting attack. The FBI later assessed that the shooter, Mohammed Saeed Al-Shamrani, had been radicalized by 2015 and was influenced by Awlaki’s propaganda.23
Much of AQAP’s activity has focused on exploiting the chaos of the Arab Spring in Yemen. AQAP acquired a significant amount of territory in 2011 and established governance in the country’s South, finally relinquishing this territory only after a Yemeni military offensive in the summer of 2012.24
AQAP further intensified its domestic activities after the overthrow of Yemen’s government by Iran-backed Houthi rebels in 2015, seizing the city of al-Mukalla and expanding its control of rural areas in southern Yemen. AQAP withdrew from al-Mukalla and other parts of the South in the spring of 2016, reportedly after the U.S.-backed Saudi–United Arab Emirates coalition had cut deals with AQAP, paying it to leave certain territory and even integrating some of its fighters into its own forces that were targeting the Houthis.25
More substantive progress has been achieved in the targeting of AQAP’s leadership. Said al-Shehri, a top AQAP operative, was killed in a drone strike in 2013. The group’s leader at the time, Nasir al-Wuhayshi, was killed in a drone strike in June 2015. Perhaps most significantly, Ibrahim al-Asiri, AQAP’s most notorious bomb maker, was killed in a U.S. strike in 2017. Since then, the tempo of U.S. drone strikes against AQAP has slowed.26
In 2018, U.N. experts estimated that AQAP commanded between 6,000 and 7,000 fighters in 2018.27 AQAP has declined since its 2015–2016 peak, losing key leaders to drone strikes and other attacks and suffering manpower losses in factional clashes and defections.28 Nevertheless, it remains a resilient force that could capitalize on the anarchy of Yemen’s multi-sided civil war to seize new territory and plan more attacks on the West.
Syria. Al-Qaeda’s Syrian affiliate, initially named the al-Nusra Front (ANF), was established as an offshoot of the Islamic State of Iraq (ISI), al-Qaeda’s Iraq affiliate, in late 2011 by Abu Muhammad al-Julani, a lieutenant of ISI leader Abu Bakr al-Baghdadi.29 ANF had an estimated 5,000 to 10,000 members and emerged as one of the top rebel groups fighting the Assad dictatorship in Syria.30 Most ANF cadres are concentrated in rebel strongholds in northwestern Syria, but the group also has small cells operating elsewhere in the country.
ANF had some success in attracting Americans to its cause. An American Muslim recruited by ANF, Moner Mohammad Abusalha, conducted a suicide truck bombing in northern Syria on May 25, 2014, in the first reported suicide attack by an American in that country.31 At least five men have been arrested inside the U.S. for providing material assistance to ANF, including Abdirahman Sheik Mohamud, a naturalized U.S. citizen who was arrested in April 2015 after returning from training in Syria and was planning to launch a terrorist attack on U.S. soldiers based in Texas.32
In recent years, the al-Qaeda network in Syria has undergone several name changes, allying itself with various Islamist rebel groups. This has made it more difficult to assess the degree of direct threat that it poses outside of Syria.
In a May 2015 interview, al-Julani stated that al-Nusra’s intentions were purely local and that, “so as not to muddy the current war” in Syria, ANF was not planning to target the West.33 In July 2016, al-Nusra rebranded itself as Jabhat Fatah Al Sham (JFS), and al-Julani stated that it would have “no affiliation to any external entity,” a move that some experts regarded as a break from al-Qaeda and others regarded as a move to obscure its ties to al-Qaeda and reduce U.S. military pressure on the group.34
In January 2017, ANF merged with other Islamist extremist movements to create a new anti-Assad coalition: Hayat Tahrir al-Sham (HTS, Organization for the Liberation of the Levant). It was estimated that HTS had 12,000 to 14,000 fighters in March 2017.35 HTS suffered many casualties as Syria’s Assad regime, backed by Iran and Russia, tightened the noose around its strongholds in northwest Syria. “Since 2017,” according to the U.S. Department of State’s 2019 Country Reports on Terrorism, “ANF has continued to operate through HTS in pursuit of its objectives.” The report further estimated that ANF’s strength had fallen to “between 5,000 to 10,000 fighters.”36
Further complicating matters surrounding al-Qaeda’s presence, another group in Syria connected to al-Qaeda, Hurras al-Din (Guardians of the Religion), was formed in March 2018.37 Among its ranks were those who defected from HTS, and its suspected emir is an Ayman al-Zawahiri acolyte.38
HTS is more pragmatic than its ultra-extremist parent organization and has cooperated with moderate Syrian rebel groups against the Assad regime, as well as against ISIS. However, the leadership of Abu Muhammad al-Julani and his tactical approach to the conflict, as well as the clear divisions within the Syrian jihad, have led to rebukes from Ayman al-Zawahiri and those who are loyal to him.39 Zawahiri has stressed the need for unity while lambasting the jihadist movement in Syria and its emphasis on holding territory in northwest Syria at the expense of intensifying the struggle against Assad.40
One entity that did pose a direct threat to the West was the Khorasan group, which was thought to comprise dozens of veterans of al-Qaeda’s operations in Afghanistan and Pakistan.41 Al-Zawahiri had dispatched this cadre of operatives to Syria, where they were embedded with ANF and—despite al-Julani’s statement that ANF was not targeting the West—charged with organizing terrorist attacks against Western targets. A series of U.S. air strikes in 2014–2015 degraded Khorasan’s capacity to organize terrorist attacks.
Al-Qaeda’s presence and activities in Syria, as well as the intent of those who once were aligned with it, are sometimes opaque, most likely on purpose. Even if offshoots of al-Qaeda are not currently emphasizing their hostility to the U.S., however, that will probably change if they succeed in further consolidating power in Syria.
The Sahel. Al-Qaeda in the Islamic Maghreb (AQIM) “has an estimated 1,000 fighters operating in the Sahel, including Algeria, northern Mali, southwest Libya, and Niger.”42 AQIM’s roots lie in the Algerian civil war of the 1990s, when the Algerian government cancelled the second round of elections following the victory of the Islamic Salvation Front (FIS) in the first round. The armed wing of the FIS, the Armed Islamic Group (GIA), responded by launching a series of attacks, executing those who were even suspected of working with the state. The group also attempted to implement sharia law in Algeria.
The GIA rapidly alienated Algerian civilians, and by the late 1990s, an offshoot, the Salafist Group for Preaching and Combat (GSPC), emerged. Its violence, somewhat less indiscriminate than the GIA’s, was focused on security and military targets. Having failed to overthrow the Algerian state, the GSPC began to align itself with al-Qaeda, and Ayman al-Zawahiri announced its integration into the al-Qaeda network in a September 2006 video. The GSPC subsequently took the AQIM name.
AQIM has carried out a series of regional attacks and has focused on kidnapping Westerners. Some of these hostages have been killed, but more have been used to extort ransoms from Western governments.43 Like other al-Qaeda affiliates, AQIM also took advantage of the power vacuums that emerged from the Arab Spring, particularly in Libya where Islamist militias flourished. The weak central government was unable to tame fractious militias, curb tribal and political clashes, or dampen rising tensions between Arabs and Berbers in the West and Arabs and the Toubou tribe in the South.
The September 11, 2012, attack on the U.S. diplomatic mission in Benghazi underscored the extent to which Islamist extremism had flourished in the region. The radical Islamist group that launched the attack, Ansar al-Sharia, had links to AQIM and shared its violent ideology. AQIM and like-minded Islamist allies also grabbed significant amounts of territory in northern Mali late in 2012, implementing a brutal version of sharia law, until a French military intervention helped to push them back.
AQIM continues to support and work alongside various jihadist groups in the region. In March 2017, the Sahara branch of AQIM merged with three other al-Qaeda or al-Qaeda–linked organizations based in the Sahel to form the Group for Support of Islam and Muslims (JNIM), an organization that has pledged allegiance to al-Qaeda emir Ayman al-Zawahiri.44
AQIM is not known to have targeted the U.S. homeland explicitly in recent years, but it does threaten regional stability and U.S. allies in North Africa and Europe, where it has gained supporters and operates extensive networks for the smuggling of arms, drugs, and people.
The Islamic State of Iraq and al-Sham and Its Affiliates. The Islamic State of Iraq and al-Sham (ISIS) is an al-Qaeda splinter group that has outstripped its parent organization in terms of its immediate threats to U.S. national interests.
The Islamic State of Iraq (ISI), the precursor to ISIS and an al-Qaeda offshoot, was perceived by some Western policymakers as having been strategically defeated following the U.S. “surge” of 2006–2007 in Iraq. However, the group benefited from America’s political and military withdrawal from Iraq in the 2010–2011 period, as well as from the chaos in Syria where the Arab Spring protests were met with bloody persecution from Bashar al-Assad.
In both Iraq and Syria, ISI had space in which to operate and a large disaffected pool of individuals from which to recruit. In April 2013, ISI emir Abu Bakr al-Baghdadi declared that the al-Nusra Front, the al-Qaeda affiliate operating in Syria, was merely a front for his operation and that a new organization was being formed: the Islamic State of Iraq and al-Sham. ISIS sought to establish an Islamic state governed by its harsh interpretation of sharia law, posing an existential threat to Christians, Shiite Muslims, Yazidis, and other religious minorities. Its long-term goals include leading a jihad to drive Western influence out of the Middle East; diminishing and discrediting Shia Islam, which it considers apostasy; and becoming the nucleus of a global Sunni Islamic empire.
With both al-Qaeda leader Ayman al-Zawahiri and ANF emir Abu Mohammed al-Julani unable to rein in al-Baghdadi, ISIS was expelled from the al-Qaeda network in February 2014. Despite this, ISIS swept through parts of northern and western Iraq and in June 2014 declared the return of the caliphate, with its capital in the northern Syrian city of Raqqa. It subsequently kidnapped and then murdered Westerners working in Syria, including American citizens.
A U.S.-led international coalition was assembled to chip away at ISIS’s control of territory. The Iraqi Army and Iranian-backed militias, supported by U.S. and coalition air strikes and special operations forces, liberated Mosul in July 2017. In Syria, U.S.-backed Syrian Democratic Forces militia liberated Raqqa in October 2017, and ISIS’s last town (Baghouz) fell in March 2019.
ISIS fighters have dispersed, have adopted insurgent tactics, and will continue to pose a regional terrorist threat with direct implications for the U.S. In January 2019, for example, four American military and civilian personnel were killed in a suicide bombing at a market in Manbij in northern Syria.45
On October 26, 2019, U.S. special operations forces killed ISIS leader al-Baghdadi in a raid in northwestern Syria’s Idlib governate near the Turkish border.46 ISIS soon named a successor, Abdullah Qardash, the nom de guerre of Mohammad Abdul Rahman al-Mawli al-Salbi. An Iraqi Turkman from Tal Afar near Mosul, Salbi is said to have met Baghdadi in Camp Bucca, a U.S. military detention center.47
The number of ISIS attacks in Iraq and Syria fell from 776 during the first four months of 2019 to 330 during the same period in 2020.48 Nevertheless, ISIS remains a significant regional threat. U.S. officials estimate that ISIS retains 14,000 to 18,000 militants in Syria and Iraq, where it is rebuilding its strength in remote desert and mountain regions.49
Although ISIS’s territorial control has been broken in Iraq and Syria, its presence has spread far beyond that territory. Terrorist groups around the world have pledged allegiance to Abu Bakr al-Baghdadi and his successor, and ISIS now has affiliates in the Middle East, in South and Southeast Asia, and throughout Africa. ISIS poses a threat to stability in all of these regions, seeking to seize territory, overthrow governments, and impose its harsh brand of Islamic law.
Although the regional ISIS groups may not pose as great a threat to the U.S. homeland as the original group in Iraq and Syria posed, they represent significant threats to U.S. allies and U.S. forces deployed overseas. An Islamic State in the Greater Sahara ambush in Niger in October 2017, for example, resulted in the death of four U.S. special operations troops.50 In addition, ISIS has made threats against embassies, including those of the U.S., in its areas of influence.51
ISIS poses an ongoing threat to life in the West. On May 3, 2015, for example, two American extremists in contact with an ISIS operative in Syria were fatally shot by police before they could commit mass murder in Garland, Texas.52
More commonly, however, the ISIS ideology has inspired individuals and small groups to plan attacks in the U.S. According to the GW Extremism Tracker, “228 individuals have been charged in the U.S. on offenses related to the Islamic State…since March 2014, when the first arrests occurred.”53
Tashfeen Malik, one of the perpetrators of the December 2, 2015, shootings that killed 14 people in San Bernardino, California, pledged allegiance to al-Baghdadi.54 ISIS also claimed responsibility for the June 12, 2016, shootings at a nightclub in Orlando, Florida, that killed 49 people. Omar Mateen, the perpetrator, had pledged allegiance to al-Baghdadi, although there is no evidence to show that the attacks were directed by ISIS.55 The group also claimed responsibility for the October 31, 2017, vehicular attack by Sayfullo Saipov in New York that killed eight.56 Saipov, too, had pledged allegiance to ISIS’s emir but did not appear to be operationally guided by ISIS.57 Such terrorist attacks, incited but not directed by ISIS, are likely to continue for the foreseeable future.
Although its appeal appears to have diminished since the fall of its caliphate in Iraq and Syria, ISIS continues to attract support from self-radicalized Americans. For example, in April 2021, two men were arrested for attempting to provide material support to ISIS. One received a prison term for providing material support, and one received a prison term for the December 2017 bombing of a New York City subway.58
ISIS has also attempted complex attacks on aviation. It claimed responsibility for the October 31, 2015, downing of a Russian passenger jet over Egypt’s Sinai Peninsula that killed 224 people and also tried to bring down a flight heading from Sydney, Australia, to Abu Dhabi by concealing an explosive device inside a meat grinder.59
ISIS had well-publicized success in attracting the support of foreign fighters. Approximately 250 from the U.S. traveled or attempted to travel to Syria.60 These individuals, who are likely to have received military training, could well pose an ongoing threat upon their return to the U.S. by involving themselves in attack planning or by helping to recruit future generations of jihadists.
ISIS had greater success attracting recruits from Europe, with approximately 6,000 departing from European countries.61 The return of foreign fighters to Europe has led to several attacks. Mehdi Nemmouche, a French citizen of Algerian origin who shot and killed four civilians at the Jewish Museum in Brussels in May 2014, for example, was an ISIS-aligned terrorist who had fought in Syria.62 In August 2015, Ayoub el-Khazzani, a Moroccan, attempted to gun down passengers in a train travelling between Amsterdam and Paris. Passengers, including two members of the U.S. Army, foiled the attack and restrained him.63
Similarly, a group of ISIS foreign fighters teamed with local Islamist terrorists in France to launch a series of suicide and gun attacks on a music venue, restaurants, cafes, and a football stadium, killing 130 and injuring 368 people in Paris in November 2015.64 Recruits from within the same network then killed 32 people and injured around 300 more in shootings and suicide bombings across Brussels, Belgium, in March 2016.65
ISIS ideology has also inspired a wave of vehicle and knife attacks in Europe, including one carried out by a Tunisian who used a truck to kill 86 people and injure 434 more at a Bastille Day celebration in Nice, France, in July 2016.66 In another such attack, in June 2017, three men killed eight people and injured 47 on or near London Bridge in London, England, by running over them or stabbing them.67 London Bridge also was the site of a November 29, 2019, knife attack by an ISIS supporter who killed two people and wounded three more before being killed by police.68
ISIS has demonstrated an interest in carrying out biological attacks. Sief Allah H., a Tunisian asylum seeker who was in contact with ISIS, and his German wife Yasmin H. were arrested in Cologne in June 2018 after they had produced ricin as part of a suspected attack.69 This was the first time that ricin had been successfully produced in the West as part of an alleged Islamist plot.
Overall, as of May 2019, ISIS had had some involvement—ranging from merely inspirational to hands-on and operational—in over 150 plots and attacks in Europe since January 2014 that had led to 371 deaths and more than 1,700 injuries.70 This includes the loss of American lives abroad. An American college student was killed in Paris in November 2015, four Americans were killed in the Brussels attack of March 2016, and another three were killed in the Nice attack of July 2016.71 Moreover, the threat is by no means confined to Europe: Americans were also killed in ISIS-claimed attacks in Tajikistan in July 2018 and Sri Lanka in April 2019.72
Terrorist Groups Operating in Afghanistan and Pakistan (Af-Pak)
According to General John W. Nicholson, former Commander of U.S. Forces–Afghanistan, “Of the 98 U.S.-designated terrorist organizations globally, 20 are located in the Afghanistan–Pakistan region. This constitutes the highest concentration of terrorist groups anywhere in the world…”73
A wide variety of Islamist terrorist groups operate from Pakistani territory, many with the support or sanction of the Pakistani state. Pakistan’s military and intelligence leaders maintain a short-term tactical approach of fighting some terrorist groups that are deemed a threat to the state while supporting others that are aligned with Pakistan’s goal of extending its influence and curbing India’s.
Pakistan’s Inter-Services Intelligence (ISI) views terrorist proxies as an extension of Pakistan’s foreign policy, and many of these groups advance Pakistan’s interests by launching attacks in Afghanistan, Kashmir, or other parts of India.
Some Islamist terrorist groups operating in Pakistan target non-Muslims and Muslim minorities deemed un-Islamic. A smaller number of anti-state terrorist outfits, like the “Pakistani Taliban” or TTP, have targeted Pakistani security forces, though their capabilities have been degraded in recent years by Pakistani military operations.74
In 2015, after a series of terrorist attacks against Pakistan’s state and security services, the government introduced a National Action Plan (NAP) to reinvigorate the country’s fight against terrorism. Pakistani military operations against TTP hideouts in North Waziristan helped to reduce Pakistan’s internal terrorist threat to some degree. According to the India-based South Asia Terrorism Portal, total fatalities in Pakistan (including terrorists/insurgents) have mostly been declining steadily since 2009.75
However, there are few signs that Pakistan’s crackdown on terrorism extends to groups that target India such as Lashkar-e-Taiba (LeT), which was responsible for the 2008 Mumbai attacks, and Jaish-e-Mohammed (JeM), which carried out an attack on the Indian parliament in 2001, another on the airbase at Pathankot in 2016, and the deadliest attack on Indian security forces in Kashmir in February 2019.76 Pakistani military and intelligence officials also maintain close links to the Taliban and the Haqqani Network.
The Haqqani Network, which operates out of Pakistan’s tribal areas, has enjoyed close links to Pakistan’s ISI since the 1970s. After the U.S. invasion of Afghanistan in 2001, the Haqqani Network launched some of the deadliest and most devastating attacks on U.S. forces in Afghanistan. These attacks include a December 2009 bombing of a CIA outpost in Khost, the deadliest attack on the CIA in the agency’s history, and two brazen assaults in 2011, including an attack on a U.S. military base in Wardak that injured 77 soldiers and an attack on the U.S. embassy that resulted in a 20-hour gun battle. Former Chairman of the Joint Chiefs of Staff Admiral Mike Mullen has described the Haqqani Network as a “veritable arm” of Pakistan’s ISI.77 The Haqqani Network maintains close links to al-Qaeda, and its operational leader, Sirajuddin Haqqani, was named Interior Minister in the Taliban’s new government in Afghanistan in August 2021.78
The threat posed by al-Qaeda in Afghanistan and Pakistan diminished somewhat after the U.S. invasion of Afghanistan in 2001 and the killing of Osama bin Laden at his hideout in Abbottabad, Pakistan, in May 2011. It was further degraded by an intensive drone campaign in Pakistan’s tribal areas in the 2010s. Nevertheless, al-Qaeda still maintains a presence in the region and could experience a resurgence with the Taliban takeover of Afghanistan, given the group’s close links to both the Haqqani Network and the Taliban. A 2020 report by the U.S. Treasury Department concluded that “as of 2020, al-Qaeda is gaining strength in Afghanistan while continuing to operate with the Taliban under the Taliban’s protection. Senior Haqqani Network figures have discussed forming a new joint unit of armed fighters in cooperation with and funded by al-Qaeda.”79
A local affiliate of ISIS, the so-called Islamic State-Khorasan (IS-K), emerged in Afghanistan and Pakistan in 2014–2015, drawing from disaffected members of the Afghan Taliban and TTP. Though its actual numbers remain modest, its high-profile, high-casualty terrorist attacks have helped it to attract followers. In March 2019, General Joseph Votel, the head of CENTCOM, said that he believed “ISIS Khorasan does have ideations focused on external operations toward our homeland.”80
Experts believe that there is little coordination between the IS branch operating in Afghanistan and the central command structure located in the Middle East. Instead, the branch draws recruits from disaffected members of the Pakistani Taliban and other radicalized Afghans and has frequently found itself at odds with the Afghan Taliban, which views IS-K as a direct competitor for financial resources, recruits, and ideological influence. U.S. officials acknowledge that even though they were not coordinating directly, U.S. air strikes and Taliban ground attacks substantially degraded IS-K capabilities in the late 2010s.81
The lack of publicly available information and the willingness of local fighters in the region to change allegiances make it difficult to know the exact number of IS-K fighters in Afghanistan at any given time. In September 2019, U.S. officials estimated that there were between 2,000 and 5,000 ISIS fighters in Afghanistan.82 A series of major defeats in 2019 led to IS-K’s “collapse” in eastern Afghanistan, according to U.S. officials.83 Since then, it appears to have changed strategies—for example, by pursuing a rapprochement with the ISI and Haqqani Network—even as it continues to battle the Afghan Taliban.84
Finally, the U.S. withdrawal from Afghanistan in August 2021 and the Afghan Taliban’s rapid takeover of the country have raised concerns that Afghanistan will once again become a safe haven for international terrorist groups, including al-Qaeda. Of particular concern is the fact that on August 19, a senior member of the Haqqani Network was put in charge of security in Kabul.85 One week later, a suicide bomber launched an attack on the Kabul airport that killed 13 U.S. military personnel and over 150 Afghans.86 The Biden Administration blamed IS-K, which took responsibility for the attack, and launched two drone strikes on IS-K targets in the week following the airport attack.87
ISIS has lost its so-called caliphate, but it remains a highly dangerous adversary capable of planning and executing attacks regionally and—at the very least—inspiring them in the West. It has transitioned from a quasi-state to an insurgency, relying on its affiliates to project strength far beyond its former Syrian and Iraqi strongholds.
Meanwhile, despite sustained losses in leadership, al-Qaeda remains resilient. It has curried favor with other Sunnis in particular areas of strategic importance to it, has focused its resources on local conflicts, has occasionally controlled territory, and has deemphasized (but not eschewed) focus on the global jihad. This approach has been particularly noticeable since the Arab Spring.
Regardless of any short-term tactical considerations, both groups ultimately aspire to attack the U.S. at home and U.S. interests abroad. While the U.S. has hardened its domestic defenses, both ISIS and al-Qaeda can rely on radicalized individuals living within the U.S. to take up the slack. Furthermore, as has been demonstrated time and again, there are ample opportunities to target Americans overseas in countries that are more vulnerable to terrorist attack. If it wishes to contain and ultimately end Islamist violence, the U.S. must continue to bring effective pressure to bear on these groups and those that support them.
The terrorist threat to the U.S. homeland from Afghanistan and Pakistan remains real and uncertain in a rapidly shifting landscape that is home to a wide variety of extremist and terrorist groups. On one hand, the capabilities of al-Qaeda, the terrorist group that is most directly focused on attacking the U.S. homeland, have been degraded since the U.S. invasion of Afghanistan in 2001. On the other hand, the U.S. withdrawal from Afghanistan and the Taliban’s rapid takeover of the country, as well as its ongoing links to the Haqqani Network, al-Qaeda, and other terrorist groups, are serious causes for concern.
In its interim peace agreement with the U.S., the Taliban ostensibly committed to preventing Afghan soil from being used to launch attacks against the U.S. homeland. However, experts remain skeptical of these commitments. The Pakistani state, meanwhile, continues to harbor and support a vibrant ecosystem of terrorist groups within its borders, creating a volatile situation even as it seeks to dissuade loyal militant organizations from attacking the U.S. for fear of blowback.
This Index assesses the threat from ISIS, al-Qaeda, and their affiliated organizations as “aggressive” for level of provocation of behavior and “capable” for level of capability.
- See “Iran,” infra.
- Peter L. Bergen, The Osama bin Laden I Know: An Oral History of al Qaeda’s Leader (New York: Free Press, 2006), pp. 82–83.
- Daniel L. Byman, “The Death of Ayman al-Zawahri and the Future of al-Qaida,” The Brookings Institution, Order from Chaos blog, November 17, 2020, https://www.brookings.edu/blog/order-from-chaos/2020/11/17/the-death-of-ayman-al-zawahri-and-the-future-of-al-qaida/ (accessed June 28, 2021).
- See, for example, United Nations Security Council, Twenty-Second Report of the Analytical Support and Sanctions Monitoring Team Submitted Pursuant to Resolution 2368 (2017) Concerning ISIL (Da’esh), Al-Qaida and Associated Individuals and Entities, S/2018/705, July 27, 2018, pp. 15 and 18, https://www.un.org/en/ga/search/view_doc.asp?symbol=S/2018/705&referer=/english/&Lang=E (accessed June 28, 2021).
- Ali Soufan, “Al-Qa`ida’s Soon-to-Be Third Emir? A Profile of Saif al-`Adl,” Combating Terrorism Center at West Point, CTC Sentinel, Vol. 14, Issue 2 (February 2021), pp. 1–21, https://ctc.usma.edu/wp-content/uploads/2021/02/CTC-SENTINEL-022021.pdf (accessed June 28, 2021).
- National Commission on Terrorist Attacks Upon the United States, The 9/11 Commission Report, released July 22, 2004, pp. 60 and 61, https://govinfo.library.unt.edu/911/report/911Report.pdf (accessed June 28, 2021). For the undated report’s official release date, see media advisory, “9-11 Commission Releases Unanimous Final Report,” National Commission on Terrorist Attacks Upon the United States, July 22, 2004, https://govinfo.library.unt.edu/911/press/pr_2004-07-22.pdf (accessed June 29, 2021). For transcripts of the commission’s 12 public hearings, see National Commission on Terrorist Attacks Upon the United States, “Hearings: Public Hearings of the National Commission on Terrorist Attacks Upon the United States,” https://govinfo.library.unt.edu/911/hearings/index.htm (accessed June 29, 2021).
- Adam Goldman, Eric Schmitt, Farnaz Fassihi, and Ronen Bergman, “Al Qaeda’s No. 2, Accused in U.S. Embassy Attacks, Was Killed in Iran,” The New York Times, updated November 27, 2020, https://www.nytimes.com/2020/11/13/world/middleeast/al-masri-abdullah-qaeda-dead.html (accessed June 28, 2021).
- James Phillips, “Why Was Iran Hiding Al Qaeda’s No. 2 in Tehran?” The National Interest, The Buzz Blog, November 20, 2020, https://nationalinterest.org/blog/buzz/why-was-iran-hiding-al-qaeda%E2%80%99s-no-2-tehran-173064 (accessed June 28, 2021).
- Michael Gordon, “Pompeo Accuses Iran of Allowing al Qaeda to Set up Headquarters,” The Wall Street Journal, updated January 12, 2021, https://www.wsj.com/articles/pompeo-accuses-iran-of-allowing-al-qaeda-to-set-up-headquarters-11610469984 (accessed June 28, 2021).
- BBC News, “Britons Convicted of Yemen Bomb Plot,” August 9, 1999, http://news.bbc.co.uk/2/hi/middle_east/415096.stm (accessed June 28, 2021).
- James Phillips, “The Yemen Bombing: Another Wake-up Call in the Terrorist Shadow War,” Heritage Foundation Executive Memorandum No. 703, October 25, 2000, http://www.heritage.org/middle-east/report/the-yemen-bombing-another-wake-call-the-terrorist-shadow-war.
- CNN, “Sources: U.S. Kills Cole Suspect,” November 5, 2002, http://www.cnn.com/2002/WORLD/meast/11/04/yemen.blast/index.html (accessed June 28, 2021).
- Greg Miller, “CIA Sees Increased Threat in Yemen,” The Washington Post, August 25, 2010, https://www.washingtonpost.com/wp-dyn/content/article/2010/08/24/AR2010082406763.html (accessed June 28, 2021).
- Jeremy Pelofsky, “Prosecutors Say al Qaeda Leader Awlaki Directed Underwear Bomber,” Reuters, February 10, 2012, https://www.reuters.com/article/us-usa-security-abdulmutallab/prosecutors-say-al-qaeda-leader-awlaki-directed-underwear-bomber-idUSTRE8191VL20120210 (accessed June 29, 2021).
- Daniel Klaidman, Kill or Capture: The War on Terror and the Soul of the Obama Presidency (New York: Houghton Mifflin Harcourt, 2012), p. 216.
- Mark Schone and Rehab el-Buri, “Fort Hood: Hasan Asked Awlaki If It Was Okay to Kill American Soldiers,” ABC News, December 23, 2009, https://abcnews.go.com/Blotter/FtHoodInvestigation/fort-hood-hasan-asked-awlaki-kill-american-soldiers/story?id=9410718 (accessed June 29, 2021).
- For more on the potential decline of AQAP’s external operations program, see Gregory D. Johnsen, “The Two Faces of Al-Qaeda in the Arabian Peninsula,” War on the Rocks, October 11, 2018, https://warontherocks.com/2018/10/the-two-faces-of-al-qaeda-in-the-arabian-peninsula/ (accessed June 29, 2021).
- Scott Shane, “The Enduring Influence of Anwar al-Awlaki in the Age of the Islamic State,” Combating Terrorism Center at West Point, CTC Sentinel, Vol. 9, Issue 7 (July 2016), pp. 15–19, https://ctc.usma.edu/app/uploads/2016/08/CTC-SENTINEL_Vol9Iss710.pdf (accessed June 29, 2021).
- BBC News, “Al-Qaeda Yemen Plane Bomb Plot Foiled by ‘Insider,’” May 8, 2012, https://www.bbc.com/news/world-us-canada-17994493 (accessed June 29, 20211).
- CBS News, “Yemen Terror Threat Prompts State Department to Evacuate Some Embassy Staff, Warn Americans to Leave Country ‘Immediately,’” August 6, 2013, https://www.cbsnews.com/news/yemen-terror-threat-prompts-state-department-to-evacuate-some-embassy-staff-warn-americans-to-leave-country-immediately/ (accessed June 29, 2021).
- Thomas Joscelyn, “Al Qaeda in the Arabian Peninsula Claims Responsibility for Charlie Hebdo Attack,” Foundation for Defense of Democracies Long War Journal, January 14, 2015, https://www.longwarjournal.org/archives/2015/01/al_qaeda_in_the_arab_2.php (accessed June 29, 2021).
- Barbara Starr and Rene Marsh, “AQAP Trying to Hide Explosives in Laptop Batteries, Official Says,” CNN, updated March 22, 2017, https://www.cnn.com/2017/03/21/politics/electronics-ban-devices-explosives-intelligence/index.html (accessed June 29, 2021).
- Thomas Joscelyn, “The Naval Air Station Pensacola Shooter Shows That Al-Qaeda Is Still a Significant Threat,” The Dispatch, May 20, 2020, https://vitalinterests.thedispatch.com/p/the-naval-air-station-pensacola-shooter (accessed June 29, 2021).
- Robin Simcox, “Ansar al-Sharia and Governance in Southern Yemen,” Hudson Institute, Center on Islam, Democracy, and the Future of the Muslim World, Current Trends in Islamist Ideology, Vol. 14 (January 2013), pp. 58–72, https://www.hudson.org/content/researchattachments/attachment/1145/20130124_ct14final.pdf (accessed June 30, 2021).
- Maggie Michael, Trish Wilson, and Lee Keath, “AP Investigation: US Allies, al-Qaida Battle Rebels in Yemen,” Associated Press, August 6, 2018, https://apnews.com/f38788a561d74ca78c77cb43612d50da (accessed June 30, 2021).
- Bill Roggio, “US Targets AQAP 8 Times in Past 3 Months,” Foundation for Defense of Democracies Long War Journal, April 2, 2019, https://www.longwarjournal.org/archives/2019/04/us-targets-aqap-8-times-in-past-3-months.php (accessed June 30, 2021).
- United Nations Security Council, Twenty-Second Report of the Analytical Support and Sanctions Monitoring Team, p. 9.
- Elisabeth Kendall, “Death of AQAP Leader Shows the Group’s Fragmentation—and Durability,” Washington Institute for Near East Policy, PolicyWatch No. 3263, February 14, 2020, https://www.washingtoninstitute.org/policy-analysis/death-aqap-leader-shows-groups-fragmentation-and-durability (accessed June 30, 2021).
- U.S. Department of State, Bureau of Counterterrorism, Country Reports on Terrorism 2017, September 2018, pp. 320–321, https://www.state.gov/wp-content/uploads/2019/04/crt_2017.pdf (accessed June 30, 2021).
- Eric Schmitt, “Al Qaeda Turns to Syria, with a Plan to Challenge ISIS,” The New York Times, May 15, 2016, http://www.nytimes.com/2016/05/16/world/middleeast/al-qaeda-turns-to-syria-with-a-plan-to-challenge-isis.html?_r=0 (accessed June 30, 2021).
- Adam Goldman, Greg Miller, and Nicole Rodriquez, “American Who Killed Himself in Syria Suicide Attack Was from South Florida,” The Washington Post, May 31, 2014, http://www.washingtonpost.com/world/national-security/american-who-killed-himself-in-syria-suicide-attack-was-from-south-florida-official-says/2014/05/30/03869b6e-e7f4-11e3-a86b-362fd5443d19_story.html (accessed June 30, 2021).
- Adam Goldman, “Ohio Man Who Trained with Jabhat al-Nusra Is Indicted on Terrorism Charges,” The Washington Post, April 16, 2015, http://www.washingtonpost.com/world/national-security/ohio-man-who-trained-with-jabhat-al-nusra-is-indicted-on-terrorism-charges/2015/04/16/8e8ded08-e455-11e4-b510-962fcfabc310_story.html (accessed June 30, 2021).
- Agence France-Presse, “Chief of Al-Qaeda’s Syria Affiliate Pledges No Attacks on the West,” May 27, 2015, https://www.yahoo.com/news/chief-al-qaedas-syria-affiliate-pledges-no-attacks-221912033.html?ref=gs (accessed June 30, 2021).
- Thomas Joscelyn, “Analysis: Al Nusrah Front Rebrands Itself as Jabhat Fath Al Sham,” Foundation for Defense of Democracies Long War Journal, July 28, 2016, https://www.longwarjournal.org/archives/2016/07/analysis-al-nusrah-front-rebrands-itself-as-jabhat-fath-al-sham.php (accessed June 30, 2021).
- Charles Lister, “Al Qaeda Is Starting to Swallow the Syrian Opposition,” Foreign Policy, March 15, 2017, http://foreignpolicy.com/2017/03/15/al-qaeda-is-swallowing-the-syrian-opposition/ (accessed June 30, 2021).
- U.S. Department of State, Bureau of Counterterrorism, Country Reports on Terrorism 2019, released June 24, 2020, p. 287, https://www.state.gov/wp-content/uploads/2020/06/Country-Reports-on-Terrorism-2019-2.pdf (accessed June 30, 2021).
- Thomas Joscelyn, “Jihadists Form ‘Guardians of the Religion’ Organization in Syria,” Foundation for Defense of Democracies Long War Journal, March 4, 2018, https://www.longwarjournal.org/archives/2018/03/jihadists-form-guardians-of-the-religion-organization-in-syria.php (accessed June 30, 2021).
- Thomas Joscelyn, “2 al Qaeda Leaders Reject Proposed Military Council in Syria,” Foundation for Defense of Democracies Long War Journal, January 30, 2019, https://www.longwarjournal.org/archives/2019/01/2-al-qaeda-leaders-reject-proposed-military-council-in-syria.php (accessed June 30, 2021).
- Thomas Joscelyn, “Analysis: Ayman al Zawahiri Calls for ‘Unity’ in Syria amid Leadership Crisis,” Foundation for Defense of Democracies Long War Journal, December 2, 2017, https://www.longwarjournal.org/archives/2017/12/analysis-ayman-al-zawahiri-calls-for-unity-in-syria-amid-leadership-crisis.php (accessed June 30, 2021).
- Thomas Joscelyn, “Zawahiri Criticizes Jihadists in Syria for Clinging to Territory Under Turkey’s Protection,” Foundation for Defense of Democracies Long War Journal, February 7, 2019, https://www.longwarjournal.org/archives/2019/02/zawahiri-criticizes-jihadists-in-syria-for-clinging-to-territory-under-turkeys-protection.php (accessed June 30, 2021).
- James Phillips, “The Rise of Al-Qaeda’s Khorasan Group: What It Means for U.S. National Security,” Heritage Foundation Issue Brief No. 4281, October 6, 2014, http://www.heritage.org/middle-east/report/the-rise-al-qaedas-khorasan-group-what-it-means-us-national-security.
- U.S. Department of State, Bureau of Counterterrorism, Country Reports on Terrorism 2019, p. 293.
- Raissa Kasolowsky and Kate Kelland, “Al Qaeda Kills British Hostage in Mali,” Reuters, June 3, 2009, https://www.reuters.com/article/us-qaeda-hostage/al-qaeda-kills-british-hostage-in-mali-idUSTRE5521HO20090603 (accessed June 30, 2021), and U.S. Department of State, Bureau of Counterterrorism, Country Reports on Terrorism 2017, p. 329.
- Thomas Joscelyn, “Analysis: Al Qaeda Groups Reorganize in West Africa,” Foundation for Defense of Democracies Long War Journal, March 13, 2017, https://www.longwarjournal.org/archives/2017/03/analysis-al-qaeda-groups-reorganize-in-west-africa.php (accessed June 30, 2021).
- BBC News, “Syria War: ‘IS Suicide Bomber’ Kills US Troops in Manbij,” January 16, 2019, https://www.bbc.com/news/world-middle-east-46892118 (accessed June 30, 2021).
- Shawn Snow, “CENTCOM Commander Releases Video of Raid on Baghdadi Compound, Which Now Looks like a ‘Parking Lot with Large Potholes,’” Military Times, October 30, 2019, https://www.militarytimes.com/news/your-military/2019/10/30/centcom-commander-releases-video-of-raid-on-baghdadi-compound-which-now-looks-like-a-parking-lot-with-large-potholes/ (accessed June 30, 2021).
- Ibrahim al-Marashi, “The Turkmen Connection to Islamic State’s New Leader,” Middle East Eye, January 28, 2020, https://www.middleeasteye.net/opinion/turkmen-connection-baghdadis-successor (accessed June 30, 2021).
- Jeff Seldin, “Data on Islamic State Attacks Could Be Masking Growing Problem, Some Fear,” Voice of America, updated May 13, 2020, https://www.voanews.com/middle-east/data-islamic-state-attacks-could-be-masking-growing-problem-some-fear (accessed June 30, 2021).
- U.S. Department of Defense, Office of Inspector General; U.S. Department of State, Office of Inspector General; and U.S. Agency for International Development, Office of Inspector General, Operation Inherent Resolve: Lead Inspector General Report to the United States Congress, January 1, 2020–March 31, 2020, p. 4, https://media.defense.gov/2020/May/13/2002298979/-1/-1/1/LIG_OIR_Q2_MAR2020_GOLD_508_0513.PDF (accessed June 30, 2021).
- Carley Petesch, “Niger May Have Arrested Militant with Ties to US Ambush,” Associated Press, April 17, 2018, https://apnews.com/d4d1fcf42f3241008227146f7b6db883 (accessed June 30, 2021).
- Ryan Browne and Jennifer Hansler, “ISIS Threat Shutters US Embassy in Democratic Republic of the Congo for More than a Week,” CNN, updated December 3, 2018, https://www.cnn.com/2018/12/03/politics/isis-threat-us-embassy-drc/index.html (accessed June 30, 2021).
- Nafees Hamid, “The British Hacker Who Became the Islamic State’s Chief Terror Cybercoach: A Profile of Junaid Hussain,” Combating Terrorism Center at West Point, CTC Sentinel, Vol. 11, Issue 4 (April 2018), pp. 30–37, https://ctc.usma.edu/app/uploads/2018/04/CTC-SENTINEL-042018-3.pdf (accessed June 30, 2021).
- George Washington, University Program on Extremism, and University of Nebraska Omaha, National Counterterrorism Innovation, Technology, and Education Center (NCITE), “GW Extremism Tracker: Terrorism in the United States.”
- Laura Wagner and Bill Chappell, “FBI: San Bernardino Shooting Is Being Investigated as a Terrorist Act,” NPR, December 4, 2015, https://www.npr.org/sections/thetwo-way/2015/12/04/458464907/alleged-san-bernardino-attacker-pledged-allegiance-to-isis (accessed June 30, 2021).
- Thomas Joscelyn, “Orlando Terrorist Swore Allegiance to Islamic State’s Abu Bakr al Baghdadi,” Foundation for Defense of Democracies Long War Journal, June 20, 2016, https://www.longwarjournal.org/archives/2016/06/orlando-terrorist-swore-allegiance-to-islamic-states-abu-bakr-al-baghdadi.php (accessed June 30, 2021).
- Peter Martinez, “ISIS Claims Responsibility for New York City Terror Attack that Killed 8,” CBS News, November 2, 2017, https://www.cbsnews.com/news/new-york-city-terror-attack-isis-claims-responsibility/ (accessed June 30, 2021).
- Jeremy B. White, “New York Truck Attack Suspect ‘Left Note Pledging Allegiance to Isis,’” The Independent, November 1, 2017, https://www.independent.co.uk/news/world/americas/new-york-truck-attack-isis-suspect-sayfullo-saipov-a8030541.html (accessed June 30, 2021).
- George Washington University, Program on Extremism, and University of Nebraska Omaha, National Counterterrorism Innovation, Technology, and Education Center (NCITE), “GW Extremism Tracker: Terrorism in the United States.”
- Reuters, “Islamic State Claims Responsibility for Egypt’s Sinai Attack,” August 26, 2018, https://www.reuters.com/article/us-egypt-security/islamic-state-claims-responsibility-for-egypts-sinai-attack-idUSKCN1LB09O (accessed June 30, 2021), and ABC [Australian Broadcasting Corporation] News, “Sydney Terror Plot: Lebanon Says It Helped Australia Foil Plane Bomb Plan Linked to Raids,” updated August 21, 2017, https://www.abc.net.au/news/2017-08-22/lebanon-says-it-helped-foil-the-sydney-plane-bomb-plot/8829234 (accessed June 30, 2021).
- Lisa Curtis, Luke Coffey, David Inserra, Daniel Kochis, Walter Lohman, Joshua Meservey, James Phillips, and Robin Simcox, “Combatting the ISIS Foreign Fighter Pipeline: A Global Approach,” Heritage Foundation Special Report No. 180, January 6, 2016, https://www.heritage.org/middle-east/report/combatting-the-isis-foreign-fighter-pipeline-global-approach.
- Agence France-Presse, “More than 6,000 Have Left Europe for Isis Jihad: EU,” The Local, April 13, 2015, https://www.thelocal.de/20150413/up-to-6000-europeans-fighting-for-islamic-groups-isis-syria-iraq (accessed June 30, 2021).
- BBC News, “Brussels Jewish Museum Murders: Mehdi Nemmouche Jailed for Life,” March 12, 2019, https://www.bbc.co.uk/news/world-europe-47533533 (accessed June 30, 2021).
- Paul Cruickshank, “Train Attack Suspect Confesses After Revelations in Academic Journal,” CNN, updated December 19, 2016, https://edition.cnn.com/2016/12/19/europe/isis-train-attack-suspect-confession/index.html (accessed June 30, 2021).
- BBC News, “Paris Attacks: What Happened on the Night,” December 9, 2015, https://www.bbc.co.uk/news/world-europe-34818994 (accessed June 30, 2021).
- Jennifer Rankin and Jon Henley, “Islamic State Claims Attacks at Brussels Airport and Metro Station,” The Guardian, March 22, 2016, https://www.theguardian.com/world/2016/mar/22/brussels-airport-explosions-heard (accessed June 30, 2021).
- BBC News, “Nice Attack: What We Know About the Bastille Day Killings,” August 19, 2016, https://www.bbc.com/news/world-europe-36801671 (accessed June 30, 2021).
- BBC News, “London Bridge Attack: What Happened,” May 3, 2019, https://www.bbc.co.uk/news/uk-england-london-40147164 (accessed June 30, 2021).
- Calla Wahlquist, Kevin Rawlinson, and Matthew Weaver, “London Bridge Attacker Named as Usman Khan, 28—as It Happened,” The Guardian, updated November 30, 2019, https://www.theguardian.com/uk-news/live/2019/nov/29/london-bridge-incident-police-city (accessed June 30, 2021).
- Florian Flade, “The June 2018 Cologne Ricin Plot: A New Threshold in Jihadi Bio Terror,” Combating Terrorism Center at West Point, CTC Sentinel, Vol. 11, Issue 7 (August 2018), pp. 1–4, https://ctc.usma.edu/wp-content/uploads/2019/01/CTC-SENTINEL-082018-final.pdf (accessed June 30, 2021).
- Unpublished data building on Robin Simcox, “European Islamist Plots and Attacks Since 2014—and How the U.S. Can Help Prevent Them,” Heritage Foundation Backgrounder No. 3236, August 1, 2017, http://www.heritage.org/europe/report/european-islamist-plots-and-attacks-2014-and-how-the-us-can-help-prevent-them.
- CBS News, “American Killed in Paris Terror Attacks,” updated November 14, 2015, https://www.cbsnews.com/news/paris-attacks-americans-us-state-department/ (accessed June 30, 2021); Camila Domonoske, “Americans Were Among Those Killed in Brussels Attacks, Says Kerry,” NPR, March 25, 2016, https://www.npr.org/sections/thetwo-way/2016/03/25/471829453/kerry-americans-were-among-those-killed-in-brussels-attacks (accessed June 30, 2021); and BBC News, “Nice Attack: Who Were the Victims?” August 19, 2016, https://www.bbc.co.uk/news/world-europe-36805164 (accessed June 30, 2021).
- BBC News, “Tajikistan ‘Attack’ Leaves Four Foreign Cyclists Dead,” July 30, 2018, https://www.bbc.co.uk/news/world-asia-45004059 (accessed June 30, 2021), and Morgan Winsor and Dragana Jovanovic, “ISIS Claims Responsibility for Sri Lanka Easter Bombings that Killed over 350,” ABC News, April 23, 2019, https://abcnews.go.com/International/isis-claims-responsibility-sri-lanka-easter-bombings-killed/story?id=62570339 (accessed June 30, 2021).
- General John W. Nicholson, Commander, U.S. Forces–Afghanistan, statement on “The Situation in Afghanistan” before the Committee on Armed Services, U.S. Senate, February 9, 2017, p. 1, https://www.armed-services.senate.gov/imo/media/doc/Nicholson_02-09-17.pdf (accessed June 30, 2021). See also transcript, “Department of Defense Press Briefing by General Nicholson in the Pentagon Briefing Room,” U.S. Department of Defense, December 2, 2016, https://www.defense.gov/News/Transcripts/Transcript-View/Article/1019029/department-of-defense-press-briefing-by-general-nicholson-in-the-pentagon-brief/ (accessed June 30, 2021).
- Madiha Afzal, “Terrorism in Pakistan Has Declined, but the Underlying Roots of Extremism Remain,” The Brookings Institution, Initiative on Nonstate Armed Actors, January 15, 2021, https://www.brookings.edu/blog/order-from-chaos/2021/01/15/terrorism-in-pakistan-has-declined-but-the-underlying-roots-of-extremism-remain/ (accessed September 11, 2021).
- Institute for Conflict Management, South Asia Terrorism Portal, “Fatalities in Terrorist Violence in Pakistan 2000–2019,” https://www.satp.org/satporgtp/countries/pakistan/database/casualties.htm (accessed June 25, 2019). Data as of June 28, 2019.
- Ankit Panda, “Jaish-e-Mohammed Leader’s ‘Global Terrorist’ Designation Is Overdue,” The Diplomat, March 4, 2019, https://thediplomat.com/2019/03/jaish-e-mohammed-leaders-global-terrorist-designation-is-overdue/ (accessed June 29, 2021).
- BBC News, “US Admiral: ‘Haqqani Is Veritable Arm of Pakistan’s ISI,’” September 22, 2011, https://www.bbc.com/news/av/world-us-canada-15026909 (accessed September 11, 2021).
- Reuters, “Taliban Name New Afghan Government, Interior Minister on U.S. Sanctions List,” September 7, 2021, https://www.reuters.com/world/india/taliban-fire-air-scatter-kabul-protesters-no-reports-injuries-2021-09-07/ (accessed September 11, 2021).
- Gregory Sullivan, Audit Director, Memorandum for Department of Defense Lead Inspector General, “Subject: Operation Inherent Resolve—Summary of Work Performed by the Department of the Treasury Related to Terrorist Financing, ISIS, and Anti-Money Laundering for First Quarter Fiscal Year 2021,” U.S. Department of the Treasury, Office of Inspector General, January 4, 2021, p. 4, https://oig.treasury.gov/sites/oig/files/2021-01/OIG-CA-21-012.pdf (accessed September 11, 2021).
- Eric Schmitt, Thomas Gibbons-Neff, Helene Cooper, and Alissa J. Rubin, “Its Territory May Be Gone, but the U.S. Fight Against ISIS Is Far from Over,” The New York Times, March 24, 2019, https://www.nytimes.com/2019/03/24/us/politics/us-isis-fight.html (accessed June 30, 2021).
- Shawn Snow, “ISIS Loses More than Half Its Fighters from US Airstrikes and Taliban Ground Operations,” Military Times, February 27, 2020, https://www.militarytimes.com/flashpoints/2020/02/27/isis-loses-more-than-half-its-fighters-from-us-airstrikes-and-taliban-ground-operations/ (accessed June 30, 2021).
- Snow, “ISIS Loses More than Half Its Fighters from US Airstrikes and Taliban Ground Operations.”
- Thomas Gibbons-Neff and Mugib Mashal, “ISIS Is Losing Afghan Territory. That Means Little for Its Victims,” The New York Times, December 2, 2019, https://www.nytimes.com/2019/12/02/world/asia/ISIS-afghanistan-baghdadi.html (accessed June 30, 2021).
- Abhinav Pandya, “The Pakistan Connection: How ISKP Became Islamabad’s Latest Proxy,” The National Interest, September 7, 2021, https://nationalinterest.org/blog/buzz/pakistan-connection-how-iskp-became-islamabad%E2%80%99s-latest-proxy-193221 (accessed September 11, 2021).
- Jamie Dettmer, “Hardline Haqqani Network Put in Charge of Kabul Security,” Voice of America, August 19, 2021, https://www.voanews.com/south-central-asia/hardline-haqqani-network-put-charge-kabul-security (accessed September 11, 2021).
- Lara Seligman, “Pentagon Prepared for ‘Mass Casualty’ Attack at Kabul Airport Hours Before Explosion,” Politico, August 30, 2021, https://www.politico.com/news/2021/08/30/pentagon-mass-casualty-attack-kabul-507481 (accessed September 11, 2021).
- Sandi Sidhu, Nick Paton Walsh, Tim Lister, Oren Liebermann, Laura Smith-Spark, and Saskya Vandoorne, “Ten Family Members, Including Children, Dead After US Strike in Kabul,” CNN, updated August 30, 2021, https://www.cnn.com/2021/08/29/asia/afghanistan-kabul-evacuation-intl/index.html (accessed September 11, 2021).