James Phillips and Jeff Smith
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 its members’ 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. With the exception of Hezbollah and other Iran-backed groups,1 those that do meet these criteria are assessed in this section.
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 the September 11, 2001, terrorist attacks, al-Qaeda’s leadership fled Afghanistan. Many members of the original cadre have been killed or captured, including Osama bin Laden, and other key al-Qaeda leaders have been killed by targeted strikes in Afghanistan, Iran, Iraq, Pakistan, Syria, Yemen, and Somalia. However, some key elements of al-Qaeda’s leadership have survived or have been replaced, and al-Qaeda’s central leadership remains a potential threat to the U.S. homeland.
Bin Laden’s successor as emir, Ayman al-Zawahiri, was forced deeper into seclusion and was killed on July 31, 2022, by two Hellfire missiles launched in a CIA drone strike in Kabul, Afghanistan. At the time, Zawahiri was living in a guesthouse owned by acting Taliban Minister of Interior Sirajuddin Haqqani—a blatant violation of the withdrawal agreement that the Taliban negotiated with the United States.3 Zawahiri’s death is not expected to affect al-Qaeda’s daily operations, which have long been controlled by the leaders of the terrorist network’s regional affiliates,4 but it could spark a leadership struggle that could weaken al-Qaeda’s influence over its far-flung affilitates. Some al-Qaeda lieutenants are believed still to be in the Afghanistan–Pakistan region; others have taken refuge in Iran.5 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).6
Like scores of other al-Qaeda members in Iran, Zeidan has 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 Afghanistan, 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.7
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.8 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 long a 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 9/11.9
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.”10 He also announced sanctions on two al-Qaeda leaders who 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 take advantage of failed or failing states in Iraq, Libya, Mali, Syria, and Yemen to advance its revolutionary agenda. 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.11
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, al-Qaeda terrorists used a boat filled with explosives to attack the USS Cole in the port of Aden, killing 17 American sailors.12 The first U.S. drone strike outside Afghanistan after 9/11 also took place in Yemen and targeted those who were connected to the attack on the Cole.13
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. In 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.14
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. Awlaki 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 2009.15 He was also tied to plots to poison food and water supplies, as well as to launch ricin and cyanide attacks,16 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 reportedly was a key influence on Major Nidal Hassan, the U.S. Army psychiatrist who perpetrated the 2009 Fort Hood shootings that killed 13 soldiers.17
Since Awlaki’s death, the number of AQAP-sanctioned external operations in the West has diminished.18 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.19
AQAP’s threat to Western security, while seemingly reduced to some extent by Awlaki’s death, remains persistent. 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 2012.20 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.21 In January 2015, two AQAP-trained terrorists murdered staff members and nearby police at Charlie Hebdo magazine in Paris.22 In 2017, aviation was targeted once again by a plan to conceal bombs in laptop batteries.23
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.24
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 2012.25
In 2015, after Iran-backed Houthi rebels overthrew Yemen’s government, AQAP further intensified its domestic activities, 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 AQAP’s fighters into its own forces that were targeting the Houthis.26
More substantive progress has been achieved in the targeting of AQAP’s leadership. In 2013, Said al-Shehri, a top AQAP operative, was killed in a drone strike, and in June 2015, the group’s leader at the time, Nasir al-Wuhayshi, was killed in another drone strike. Perhaps most significantly, Ibrahim al-Asiri, AQAP’s most notorious bomb maker, was killed in a U.S. strike in 2017. The number of U.S. air and drone strikes targeting AQAP terrorists peaked at 131 in 2017 before declining steadily to 41 in 2018 and four in 2020. The Biden Administration launched two air or drone strikes in 2021 but had launched none as of the time this book was being prepared in 2022.27
In 2018, U.N. experts estimated that AQAP commanded between 6,000 and 7,000 fighters.28 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.29 According to a February 2022 U.N. report, AQAP now has approximately 3,000 fighters.30 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.31 By the end of 2016, ANF—now renamed Jabhat Fatah Al Sham (JFS)—“had up to 10,000 fighters” and was “one of the most active rebel groups [fighting the Assad dictatorship] in Syria.”32 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.33 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.34
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.35 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 designed to obscure its ties to al-Qaeda and reduce U.S. military pressure on the group.36
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). In March 2017, it was estimated that HTS had 12,000 to 14,000 fighters.37 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 2020 Country Reports on Terrorism, “ANF has continued to operate through HTS in pursuit of its objectives.” The report further estimates that ANF’s strength has fallen to “between 5,000 to 10,000 fighters.”38
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 2018.39 Among its ranks were those who defected from HTS, and its suspected emir is an Ayman al-Zawahiri acolyte.40 Hurras al-Din leaders have criticized HTS for its close ties to Turkey and were among the rival Islamist extremists arrested by HTS in January and February 2022 in Idlib province, the last remaining stronghold of armed resistance in northwest Syria.41
HTS is more pragmatic than its ultra-extremist parent organization and has cooperated with moderate Syrian rebel groups against both the Assad regime and 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.42 Zawahiri has stressed the need for unity while condemning the jihadist movement in Syria and its emphasis on holding territory in northwest Syria at the expense of intensifying the struggle against Assad.43
One entity that posed a more immediate 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.44 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 and 2015 degraded Khorasan’s capacity to organize terrorist attacks, and the group’s prominence faded after two of its top leaders were killed by U.S. air strikes in 2016.45
Al-Qaeda’s presence and activities in Syria, as well as the intent of those who once were aligned with it, remain opaque. 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.”46 AQIM’s roots lie in the Algerian civil war of the 1990s after the Algerian government cancelled the second round of elections in 1992 following the victory of the Islamic Salvation Front (FIS) in the first round. The FIS’s armed wing, 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.47 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 with 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.48 AQIM remains an active threat in Algeria, Libya, Mali, Niger and Tunisia and has expanded its operations in Burkina Faso and Cote D’Ivoire in recent years. Although AQIM is not known to have targeted the U.S. homeland explicitly, 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.
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. Some Western policymakers wrongly perceived the Islamic State of Iraq (ISI), the precursor to ISIS and an al-Qaeda offshoot, as having been strategically defeated following the U.S. “surge” of 2006–2007 in Iraq. However, although decimated by U.S.-led counterterrorism operations, it exploited the more permissive environment after the 2011 U.S. military withdrawal from Iraq as well as the mounting chaos in Syria after Arab Spring protests were brutally suppressed by the Assad regime.
In both Iraq and Syria, ISI had space in which to operate and a large pool of disaffected 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, thereby posing an existential threat to Christians, Shiite Muslims, Yazidis, and other religious minorities as well as to Sunni Muslims that rejected its leadership. 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, the U.S.-backed Syrian Democratic Forces militia liberated Raqqa in October 2017, and ISIS’s last stronghold in the town of 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.49
On October 26, 2019, U.S. special operations forces killed ISIS leader al-Baghdadi in a raid in northwestern Syria’s Idlib province near the Turkish border.50 ISIS soon named a successor, Abu Ibrahim al-Hashimi al-Qurayshi, the nom de guerre of Amir Muhammad Sa’id Abdal-Rahman al-Mawla. Qurayshi was killed in a February 3, 2022, U.S. special operations raid, also staged in Idlib province.51 On March 10, 2022, in a recorded audio message that was distributed online, ISIS announced that it had a new leader, Abu al-Hassan al-Hashemi al-Quraishi. Iraqi and Western intelligence officials revealed that the new leader’s real name was Juma Awad al-Badri and that he was an Iraqi whose brother was the slain former caliph Abu Bakr al-Baghdadi.52 Turkish officials claimed that the new ISIS leader was arrested in Istanbul on May 26, 2022, but that arrest has not been officially confirmed.53
The number of ISIS attacks in Iraq and Syria declined from 2019 to 2020 and fell further in 2021, although its attacks increased in Afghanistan and West Africa. “In 2021,” according to Israel’s Meir Amit Intelligence and Terrorism Information Center, “a total of 8,147 people were killed or wounded in ISIS attacks, compared to 9,068 people in 2020.”54 Nevertheless, ISIS remains a significant regional threat. U.S. officials estimate that ISIS retains 11,000 to 18,000 militants in Syria and Iraq, where it is rebuilding its strength in remote desert and mountain regions.55 In January 2022, during an operation designed to free more than 3,500 members of ISIS who were being held at a prison maintained by the Syrian Democratic Forces militia in northeastern Syria, scores if not hundreds of ISIS terrorists escaped during almost two weeks of fighting.56
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 successors, and ISIS now has affiliates in the Middle East, in South and Southeast Asia, and in Africa. ISIS poses a threat to stability in all of these regions as it seeks 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.57 ISIS-Greater Sahara also has staged attacks on French and Malian military forces in Mali. By 2022, ISIS affiliates in Africa had established a tempo of lethal attacks that surpassed that of its parent organization in Iraq and Syria.58 In addition, ISIS has made threats against embassies, including those of the U.S., in its areas of influence.59
ISIS also 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.60 An apparent ISIS plot to assassinate former President George W. Bush in Dallas, Texas, that was foiled in early 2022 resulted in the arrest of an Iraqi man living in the U.S. who was linked to ISIS operatives. The man, Shihab Ahmed Shihab, visited Dallas in November 2021 to videotape the approaches to the former President’s home and recruited a team that he hoped to smuggle into the country over the Mexican border.61 As of March 2022, the George Washington University Extremism Tracker reported that “238 individuals have been charged in the U.S. on offenses related to the Islamic State (also known as IS, ISIS, and ISIL) since March 2014, when the first arrests occurred.”62
More commonly, however, the ISIS ideology has inspired individuals and small groups to plan attacks in the U.S. that exhibit little or no apparent contact with the terrorist organization. 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.63 ISIS claimed responsibility for the June 12, 2016, shootings that killed 49 people at a nightclub in Orlando, Florida. Omar Mateen, the perpetrator, had pledged allegiance to al-Baghdadi, but there is no evidence to show that the attacks were directed by ISIS.64 The group also claimed responsibility for the October 31, 2017, vehicular attack by Sayfullo Saipov in New York that killed eight.65 Saipov also had pledged allegiance to ISIS’s emir but did not appear to be operationally guided by ISIS.66 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.67
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, which 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.68
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 to join its ranks.69 These individuals, who likely 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.70 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.71 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.72
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 2015.73 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 2016.74
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 2016.75 In June 2017, in another such attack, three men killed eight people and injured 47 on or near London Bridge in London, England, by running over them or stabbing them.76 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.77
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.78 This was the first time that ricin had been successfully produced in the West as part of an alleged Islamist terrorist plot.
Overall, as of May 2019, ISIS was known to have had some involvement—ranging from merely inspirational to hands-on and operational—in more than 150 plots and attacks in Europe since January 2014 that had led to 371 deaths and more than 1,700 injuries.79 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 March 2016 Brussels attack, and another three were killed in the July 2026 Nice attack.80 Moreover, the threat is by no means confined to Europe: Americans were also killed in attacks for which ISIS claimed responsibility in Tajikistan in July 2018 and Sri Lanka in April 2019.
Terrorist Groups Operating in Afghanistan and Pakistan (Af-Pak)
A wide variety of Islamist fundamentalist and terrorist groups operate in Afghanistan and Pakistan. The direct threat posed by al-Qaeda to the U.S. homeland has diminished since the 9/11 terrorist attacks, the U.S. invasion of Afghanistan in 2001, and the killing of Osama bin Laden at his Abbottabad, Pakistan, hideout in May 2011 and was further degraded by an intensive drone campaign in Pakistan’s tribal areas and operations by Pakistani security forces. Nevertheless, the residual presence of al-Qaeda and the emergence of a regional offshoot of the Islamic State remain serious concerns.
The Taliban’s takeover of Afghanistan in August 2021 amid a chaotic U.S. withdrawal from the country has altered the terrorist landscape, providing a more permissive environment to a wide variety of terrorist and extremist groups. Of particular concern is the prominent role the Haqqani Network has assumed in the new Taliban government.81 The Haqqani Network, a loyal proxy of Pakistan’s Inter-Services Intelligence (ISI) agency, allied itself with the Taliban during the Afghan War and became integrated with its leadership structure under the leadership of Sirajuddin Haqqani. Throughout the course of the war, the Haqqani Network was responsible for many of the deadliest attacks on U.S. and Afghan forces,82 including an attack on the U.S. embassy in Afghanistan and the single deadliest attack on the CIA in the agency’s history. Today, Sirajuddin Haqqani serves as Afghanistan’s interior minister, and other members of his network have assumed cabinet positions.
The Haqqanis maintain close links to al-Qaeda. According to a 2021 U.N. report, the Haqqani Network “remains a hub for outreach and cooperation with regional foreign terrorist groups and is the primary liaison between the Taliban and Al-Qaida.”83
Reports of an ISIS presence in Afghanistan first began to surface in 2014, and the group slowly gained a small foothold in the country in subsequent years. The lack of publicly available information and the willingness of local fighters in the region to change allegiances with little thought make it next to impossible to know the exact number of Islamic State 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.84 In arguably its highest-profile attack, the Islamic State in Afghanistan claimed responsibility for a deadly suicide bombing at the Kabul airport in August 2021 that “killed more than 170 civilians and 13 U.S. soldiers.”85
Experts believe that there is little coordination between the Islamic State 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, with which it competes for resources, territory, and recruits.
While the Islamic State and the Afghan Taliban have engaged in heavy fighting in recent years, the Haqqani Network has maintained links to the Islamic State, which may have itself splintered into different factions. In 2020, the group appointed a former midlevel Haqqani commander as its new leader, and Afghanistan’s intelligence agency killed five members of a joint cell of Haqqani Network and Islamic State fighters and arrested eight others.86 Scholar Theo Farrell contends that “the Haqqanis have the deepest links with [the Islamic State] of any faction within the Taliban.”87
Ultimately, both the Islamic State in Afghanistan and al-Qaeda continue to pose the greatest threat to the U.S. homeland. In March 2019, General Joseph Votel, then Commander, U.S. Central Command, said that he believed the Islamic State in Afghanistan “does have ideations focused on external operations toward our homeland.”88 In late 2021, a senior Biden Administration official warned that both al-Qaeda and the Islamic State in Afghanistan are intent on conducting terrorist attacks on the United States and that “[w]e could see ISIS-K generate that capability in somewhere between 6 or 12 months.”89
Pakistan remains both a victim of and a key benefactor of regional terrorist groups. Pakistan’s ISI maintained links to terrorist groups operating in disputed Kashmir and in Afghanistan for decades, viewing them as an extension of Pakistani foreign policy. Most of the terrorist groups operating in the country maintain some ties with the Pakistani military–intelligence establishment. Several domestic terrorist groups focus their attacks on non-Muslims and Muslim minorities deemed un-Islamic inside Pakistan. A smaller number of terrorist groups, like the Pakistani Taliban, are hostile to the Pakistani state and have carried out countless attacks on civilian and military targets inside the country.
After a bloody wave of terrorism by the Pakistani Taliban between 2006 and 2016, a series of military operations in Pakistan’s Federally Administered Tribal Areas and peace deals struck with local militant commanders caused terrorism inside Pakistan to subside in the late 2010s.90 However, since the takeover of Afghanistan by the Haqqani Network and Afghan Taliban, Pakistan has again witnessed a spike in bombings and terrorist attacks by the Pakistani Taliban. Pakistan has sought to pressure the Afghan Taliban and the Haqqani Network to use their influence to persuade the Pakistani Taliban to end these attacks, but with only mixed success. Despite Pakistan’s willingness to shelter the Afghan Taliban leadership throughout the course of the Afghan War, relations between the Afghan Taliban and the Pakistani government remain difficult.91
Nevertheless, Pakistan’s continued support for terrorist groups that have links to others like al-Qaeda, the Afghan Taliban, and the Haqqani Network undermine U.S. counterterrorism goals in the region and pose an ongoing threat to the U.S. homeland and its interests and partners abroad. Pakistan’s ongoing patronage of terrorist groups operating in Kashmir, like Lashkar e Taiba and Jaish e Mohammed (and their various offspring and splinter groups), has ensured continued volatility in the Kashmir dispute and prevented any breakthrough in India–Pakistan diplomatic relations. 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 foreign policy goals.
ISIS has lost its so-called caliphate, but it remains a highly dangerous adversary that is 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. homeland 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 answer their call for jihadist terrorism. 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 in South Asia. On the other hand, the U.S. withdrawal from Afghanistan and the Taliban/Haqqani Network takeover of the country have generated a great deal of uncertainty about Afghanistan’s future and the panoply of terrorist and extremist groups operating in that space, including the local branch of the Islamic State.
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. For its part, Pakistan continues to harbor and support a vibrant ecosystem of terrorist groups within its borders.
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.
 Jonathan Schroden, “What Zawahri’s Death Tells Us About Afghanistan’s Future,” Politico, August 2, 2022, https://www.politico.com/news/magazine/2022/08/02/zawahris-death-and-afghanistans-future-00049239 (accessed September 12, 2022).
 Matthew Levitt and Aaron Zelin, “What Zawahiri’s Death Means for al-Qaeda and Its Branches,” Washington Institute for Near East Policy, PolicyWatch No. 3636, August 2, 2022, https://www.washingtoninstitute.org/policy-analysis/what-zawahiris-death-means-al-qaeda-and-its-branches (accessed September 12, 2022).
 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://documents-dds-ny.un.org/doc/UNDOC/GEN/N18/201/01/PDF/N1820101.pdf?OpenElement (accessed June 14, 2022).
 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 14, 2022).
 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 17, 2022). 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 17, 2022). 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 17, 2022).
 Reuters, “Israeli Operatives Killed al Qaeda’s No. 2 Leader in Iran in August—New York Times,” November 14, 2020, https://www.reuters.com/article/usa-security-qaeda/israeli-operatives-killed-al-qaedas-no-2-leader-in-iran-in-august-new-york-times-idUSKBN27U02L (accessed June 15, 2022).
 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 17, 2022).
 Michael R. 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 17, 2022).
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 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.
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 Daniel Klaidman, Kill or Capture: The War on Terror and the Soul of the Obama Presidency (New York: Houghton Mifflin Harcourt, 2012), p. 216.
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 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 17, 2022).
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 Smith, “The Haqqani Network: The New Kingmakers in Kabul.”