Lessons from the War in Kosovo

Report Europe

Lessons from the War in Kosovo

July 22, 1999 22 min read

Authors: James Phillips and James Anderson

For some, the outcome of the war in Kosovo is a definitive foreign policy victory that vindicates the concept of "humanitarian" interventions, and a military triumph that affirms the primacy of air power. Some even speak of a "Clinton Doctrine" that would commit the United States to using force to halt the violent oppression of ethnic groups wherever and whenever such oppression occurs.

The time is ripe for a sober assessment of Operation Allied Force, the North Atlantic Treaty Organization's (NATO) 78-day air campaign against Yugoslavia, as well as the ensuing peace agreement. Unless policymakers draw the correct lessons from this intervention based on a realistic appraisal of both the short- and long-term costs of the war, the United States risks lurching unprepared into future Kosovo-like operations.

A critical appraisal should provide decision-makers with both a framework for considering intervention in general and insight into how the United States should respond to future humanitarian crises. This understanding, in turn, could clarify what the vital interests of the United States are and what its national security strategy should be for the next century.


Despite the Clinton Administration's claims, NATO did not win a clear-cut victory in Kosovo. Although the military contest was one-sided, the end results were decidedly mixed. The gradually escalating air campaign clearly failed to avert a humanitarian disaster. In fact, the aerial bombardment provided Yugoslavian President Slobodan Milosevic with the pretext to accelerate and intensify his ethnic cleansing campaign. The bulk of the atrocities against the ethnic Albanians in Kosovo occurred after the air war commenced on March 24. And despite the rhetoric about the war's "humanitarian" aim, NATO kept most of its warplanes above 15,000 feet to minimize allied casualties, which not only reduced their effectiveness in halting Serb aggression against the Kosovar Albanians, but also increased the collateral damage, including the accidental deaths of innocent Albanians and Serbs. U.S. participation in Operation Allied Force involved diplomatic costs as well, souring relations with both Russia and China.

Peace Agreement Yields NATO Concessions

There was also a diplomatic price to be paid to President Milosevic. Although he was forced to withdraw his military forces from Kosovo, he actually pocketed a better diplomatic deal after the war than the one he rejected at the February 1999 peace talks in Rambouillet, France. NATO essentially settled for what could be described as "Rambouillet-lite" by making three key concessions:

  1. Putting a peacekeeping force under United Nations--not NATO--auspices.  The international peacekeeping force deployed in Kosovo (KFOR) is organized under the auspices of the U.N., not NATO as the NATO allies had demanded at Rambouillet. This arrangement already has complicated the postwar peacekeeping situation by allowing non-NATO members, such as Russia, to participate and by giving two powers that were critical of NATO's intervention--Russia and China--veto power over KFOR policies in the U.N. Security Council.

  2. Restricting KFOR peacekeepers to Kosovo. KFOR's deployment is limited to Kosovo, without any access to Serbia, as envisioned at Rambouillet. This means that President Milosevic, indicted by the U.N.'s International War Crimes Tribunal on May 24, 1999, will be safe from arrest by KFOR troops.

  3. Allowing Yugoslavia to retain legal sovereignty over Kosovo. One of the crucial allied demands made at Rambouillet--a referendum that would determine Kosovo's future status after a three-year period of autonomy--was discarded summarily in the final peace agreement. The referendum held out the promise of independence for Kosovo and was the principal reason most leaders of the Kosovo Liberation Army (KLA) agreed to the Rambouillet plan. This critical concession sets the stage for continued instability and bloodletting in Kosovo.

Collectively, these terms constitute a significant weakening of the ultimatum NATO issued at Rambouillet. In return, President Milosevic made only one major concession--to reduce the number of Serbian troops deployed in Kosovo from 5,000 to a few hundred.

KFOR's Open-Ended Mission

The KFOR peacekeeping force charged with implementing the Kosovo peace agreement faces a costly, risky, and open-ended commitment. Its mission includes providing a secure environment for the return of hundreds of thousands of refugees expelled by Yugoslavian forces during the air war. In addition, KFOR will have to interpose its troops between the Albanians and Serbs in Kosovo to prevent reprisals while assisting the civilian agencies as they begin the onerous task of rebuilding the war-torn province.

As part of this peacekeeping force, the United States committed itself to another open-ended Balkans deployment. Taking into account the need to rotate troops, the deployment of 7,000 U.S. troops, in effect, will tie up the equivalent of a U.S. Army division for many years to come.

U.S. participation in the Kosovo peacekeeping operation will be dangerous as well. On July 18, two soldiers were killed in Kosovo when their armored personnel carrier accidentally overturned. U.S. servicemen have come under hostile fire in recent weeks as well.

Since the end of the Vietnam War, more U.S. troops have been killed by hostile fire in peacekeeping operations in Lebanon and Somalia (285) than in military actions against Iraq, Panama, and Grenada (189).1 Although such casualties could be justified in military operations that advance vital national interests, they have been rightly questioned when incurred in peacekeeping operations in which U.S. interests are minimal or nonexistent.

Operation Allied Force produced a fragile peace that did not reconcile Yugoslavia's claim of sovereignty over Kosovo with the Kosovars' burgeoning independence movement. It is difficult to see how KFOR can obtain the KLA's long-term cooperation while implementing an accord that admits Yugoslavia's sovereignty over Kosovo. If KFOR merely freezes a tense situation without addressing the underlying causes of that tension, the result could be a protracted, low-level conflict in which the KLA, or recalcitrant Serbs, attack KFOR to drive it out.

KFOR's open-ended peace enforcement mission already is complicated by the participation of a Russian troop contingent slated to reach 3,600 soldiers. There are concerns that the Russians could act as surrogates for the Serbs, their traditional Slavic allies, and become targets for vengeful ethnic Albanians. They also could undermine KFOR's unity of command by taking disruptive actions, such as the June 12 seizure of the Pristina airport by 200 Russian troops, who unilaterally abandoned their peacekeeping duties in Bosnia. Either possibility would increase the danger to U.S. soldiers.

Even if U.S. troops manage to avoid further casualties during the KFOR peacekeeping mission, the strategic and economic expenses will be burdensome. If the U.S. experience in Bosnia is any indication, another Balkan peacekeeping deployment will be a costly, long-term endeavor. The deployment of 7,000 U.S. troops in Kosovo will drain the budget of the U.S. Department of Defense of an estimated $2 billion to $3.5 billion per year.2


The costs and risks of a protracted commitment to the peacekeeping mission in Kosovo make it imperative that policymakers draw the proper lessons from the war NATO fought in Yugoslavia.

Lesson #1. The United States never should underestimate the resolve of determined adversaries to resist military threats and pressure.

Before Operation Allied Force, the Clinton Administration backed itself and NATO into a rhetorical corner by repeatedly threatening Yugoslavian President Milosevic without taking meaningful action. The threats included diplomatic warnings and show-of-force demonstrations, such as Operation Determined Falcon in June 1998. This NATO exercise, which involved hundreds of warplanes, evidently failed to impress Milosevic of NATO's resolve.

President Milosevic became emboldened by the disconnect between NATO's increasingly strident rhetoric and lack of meaningful action. Convinced that the threats were nothing more than bluffs, Milosevic escalated his repressive policies in Kosovo. For their part, the United States and its NATO allies ultimately convinced themselves that only military intervention could restore the organization's credibility. NATO thus found itself impaled by not only a determined adversary but also a crisis of confidence of its own making.

President Bill Clinton also underestimated Milosevic's determination to resist military pressure. He belatedly admitted that he had failed to recognize Yugoslavia's capacity to withstand the bombing campaign, presuming Milosevic would submit to NATO's demands and halt ethnic cleansing operations after a "couple of days" of bombing.3 President Clinton should have known better. Milosevic's previous ethic cleansing campaigns in Bosnia and Croatia had ended only when he faced the combined impact of NATO air strikes, a Croatian ground offensive, and efforts to train and equip Bosnia's army. In addition, years of air strikes against Saddam Hussein had failed to dislodge the Iraqi leader or destroy his ability to manufacture weapons of mass destruction. President Clinton's failure to anticipate Milosevic's willingness to resist the opening salvos of Operation Allied Force forced NATO to improvise its air campaign.

Lesson #2. Low-risk, incremental air campaigns are insufficient to win wars.

For most of the air campaign, NATO engaged in a slow-moving military escalation reminiscent of the feckless strategy of the United States in the Vietnam War. Self-imposed targeting restrictions allowed Yugoslavian forces to escalate the ethnic cleansing. In addition, they skillfully dispersed and concealed their military troops and equipment to minimize the effectiveness of Operation Allied Force. It is now clear that NATO dramatically overestimated its destruction of enemy tanks, artillery pieces, and armor vehicles.4 Yugoslavia's military suffered relatively light losses until the last two weeks of fighting, when a bold offensive by the KLA flushed the Yugoslavian army into the open so that a series of B-52 bomber strikes could inflict devastating casualties.5

It would be unwise to conclude that President Milosevic agreed to the peace deal solely because of NATO's air campaign. This superficial assessment would ignore not only the impact of the KLA ground offensive, but also the broader political dynamics, such as intense pressure on Milosevic from Russia to sign a peace agreement.

Moreover, there is little doubt that U.S. adversaries will learn from Operation Allied Force how to offset U.S. aerial advantages in future conflicts. North Korea already has spent decades "digging in" to protect its military assets. Other U.S. adversaries can be expected to follow suit--dispersing, concealing, and burrowing their military assets to evade detection and destruction by U.S. air strikes.

Lesson #3. Low-risk, high-altitude air campaigns are ill-suited to achieve humanitarian objectives.

Once Operation Allied Force began, it quickly became apparent that high-altitude NATO air strikes could not prevent the door-to-door massacres of ethnic Albanians carried out by dispersed units of Serbian police and paramilitary groups. The Clinton Administration failed to make adequate contingency plans in the event the bombing did not work.

Tragically, the chief victims of the disconnect between President Clinton's lofty rhetoric about stopping the ethnic slaughter and the bloodletting on the ground were the Kosovars themselves. Serbian forces killed thousands of ethnic Albanians, uprooted 1.4 million from their homes, and expelled more than 850,000 refugees from Kosovo. Most of these atrocities occurred after Operation Allied Force began its campaign on March 24. Despite its best intentions, Operation Allied Force demonstrated that air power has only limited ability to prevent humanitarian abuses. There is no reason to believe air power will be any more effective in preventing future door-to-door killing sprees by determined ground forces.

Lesson #4. If the United States takes sides in a civil war, then it should consider harnessing the military potential of the indigenous forces willing to fight and die for their territory.

NATO's air campaign was not solely responsible for forcing President Milosevic to withdraw his forces from Kosovo. It had significant help from the ethnic Albanian resistance movement operating in Kosovo. Far from being a ragtag group of bandits, as commonly portrayed in the Western press, the KLA quickly developed into a well-organized guerrilla army--strong testimony to its resiliency despite relentless Yugoslavian attacks. Yet NATO sluggishly moved to exploit the KLA's military potential, partly because of its natural bias against working with guerrilla forces. Operation Allied Force probably would have been more effective if the United States had moved earlier to harness the KLA's military potential.6

The Clinton Administration should have known that U.S. support of indigenous forces was effective in advancing U.S. foreign policy aims in the past. In the 1980s, for example, President Ronald Reagan's decision to back anticommunist guerrillas in Nicaragua and Afghanistan demonstrated how successful such a strategy can be. The sustained support of guerrilla groups can reduce the likelihood that U.S. combat forces will become embroiled in conflicts that do not threaten vital U.S. security interests.

Lesson #5. The United States should use military force only when its vital interests are threatened.

The Clinton Administration shied away from discussing whether Yugoslavia threatened vital U.S. interests. This is unfortunate because, as Joseph Nye, Jr., a noted Harvard strategist, recently observed, "In a democracy, such political struggles over the exact definition of national interests--and how to pursue them--are both inevitable and healthy."7

NATO intervened in Kosovo not to achieve clearly defined strategic goals, but to assuage a humanitarian crisis. Although strategic arguments like preventing the spread of the war or bringing stability to the Balkans were made after the conflict began, it is clear that the principal reason for waging the air campaign was to halt the ethnic cleansing inside Kosovo.8 In his March 24 address to the country, President Clinton declared the United States was "act[ing] to protect thousands of innocent people in Kosovo from a mounting military offensive."

The idea that the United States is obligated to intervene militarily to stop human rights violations in certain countries raises troubling strategic and moral issues. It raises questions about why some people's human rights appear more important than those of others. This is not an academic question; clearly, the United States and its NATO partners lack the resources necessary to intervene everywhere to stop every evil.

The Clinton Administration's participation in Operation Allied Force went far beyond the traditional conception of U.S. security interests in Europe.9 The main U.S. strategic interest in Europe has been to prevent any hostile power or set of powers from dominating that continent. Although brutal in his repression of Kosovar Albanians, President Milosevic did not threaten the balance of power in Europe. By ruling out the commitment of ground troops, even the Clinton Administration tacitly admitted that the situation in Kosovo did not threaten vital U.S. security interests.

Lesson #6. Military intervention should strive to achieve goals that are clearly defined, decisive, attainable, and sustainable.10

Unable to compel President Milosevic to stop his ethnic cleansing campaign in Kosovo, NATO resorted to trying to achieve essentially non-political objectives, such as returning refugees to Kosovo. As a result, the peace agreement sidesteps, but does not resolve, the key issue of the territory's ultimate political status.11

Perhaps nowhere is NATO's lack of coherence in its objectives more evident than its characterization of, and subsequent dealings with, President Milosevic. The Clinton Administration demonized him as the moral equivalent of Nazi Germany's Adolf Hitler. In a discussion of Kosovo, President Clinton declared,

What if someone had listened to Winston Churchill and stood up to Adolph Hitler earlier? How many people's lives might have been saved? And how many American lives might have been saved?12

Yet, at the same time, President Clinton readily accepted Milosevic as NATO's negotiating partner. On May 6, 1999, foreign ministers from the Group of Eight (G-8) industrial countries13 released a statement, now known as the Bonn Agreement, in which they outline their desired political solution to the war in Kosovo. Nowhere in the agreement do the participating states demand the removal of President Milosevic from power. Indeed, they stress the need to take into account the "principles of sovereignty and territorial integrity of the Federal Republic of Yugoslavia" in resolving the conflict.14 NATO accepted similar language in the accord that ended the war without even mentioning the fact that Milosevic had been indicted as an international war criminal.

The chasm between NATO's rhetoric and reality raises troubling questions about the purpose of NATO's intervention in Kosovo. If President Milosevic is so evil, then why let him stay in power and deal with him as a negotiating partner? If he is the root cause of the problem, then why not cut out the root? And why make a leader with a well-documented record of breaking agreements a party to yet another one? NATO's failure to answer these pivotal issues ensures a muddled peace agreement, which merely defers resolution of Kosovo's ultimate political status.

Lesson #7. Political leaders should create conditions that would permit the overwhelming application of military force.

The Clinton Administration's support of targeting restrictions in Operation Allied Force crimped the military's ability to apply force in a potentially decisive manner.15 As a result, the opening phases of the bombing campaign clearly lacked the intensity of Operation Desert Storm, the U.S.-led effort to oust Iraqi forces from Kuwait in 1991. In addition, NATO's political leaders could not agree to blockade Yugoslavian ports, thus allowing Yugoslavia to refuel its military forces even though its domestic oil refineries had been destroyed by air strikes.

The restrictions, combined with the inherent limitations of air power, resulted in an air campaign that failed to halt President Milosevic's ethnic cleansing campaign inside Kosovo. Even air attacks within Serbia itself were hampered by Vietnam-style incrementalism throughout much of the campaign. This diminished both the physical and psychological impact of Operation Allied Force, thus making a protracted air campaign necessary.

Coalition warfare requires firm leadership. As the NATO member that provided most of the aircraft and flew most of the bombing missions during the campaign, the United States should have pushed harder to convince its allies of the importance of applying overwhelming force. The political failure to create conditions whereby military force could have been applied more quickly and decisively partially offset NATO's technological advantages.

Lesson #8. Displaying an aversion to casualties reduces military effectiveness and unnecessarily protracts military intervention.

The desire to avoid any NATO or U.S. casualties undermined Operation Allied Force and exposed one of the inherent weaknesses of waging so-called humanitarian wars. It severely limited NATO's ability to curb Yugoslavian ethnic cleansing within Kosovo. The United States was unwilling to unleash its military assets, such as Apache AH-64 attack helicopters, that could have inflicted greater punishment on the Yugoslavian ground forces in Kosovo.

Operational restrictions to limit NATO casualties, which forced NATO pilots to try to distinguish between military and non-military targets from high altitudes, contributed to tragic mistakes in the bombing campaign. Unfortunate incidents included the accidental bombing of a refugee convoy in Kosovo and a civilian train in Serbia. Tragically, the determination to avoid casualties resulted in a longer and perhaps bloodier campaign.

Lesson #9. Military intervention in the Balkans should not jeopardize the ability of the United States to meet more important security commitments elsewhere in the world.

The military intervention in Kosovo reduced the capacity of the United States to respond to other, more important security commitments around the globe, such as those in the Middle East and on the Korean Peninsula. The U.S. military commitment in Kosovo involved a large number of transport aircraft and specialized reconnaissance, surveillance, and radar-jamming planes. It forced the U.S. Navy to reshuffle its deployment of aircraft carriers, leaving forces assigned to defend South Korea without a carrier presence. Operation Allied Force also severely depleted the U.S. arsenal of conventionally armed air-launched cruise missiles, which the United States would need in the event of a crisis in the Persian Gulf or on the Korean Peninsula. The United States is fortunate indeed that rogue states like North Korea and Iraq did not exploit the diversion of U.S. military assets to the Balkans. Yet the next time the United States commits significant military resources to a strategic backwater like Yugoslavia, it may not be so lucky.

In any event, the open-ended deployment of 7,000 U.S. troops as part of the 50,000-strong peacekeeping force in Kosovo will strain the ability of the U.S. armed forces to execute their assigned missions elsewhere in the world. The rotation schedule of training for peacekeeping missions and retraining for warfighting afterward means the U.S. commitment to KFOR will divert 21,000 troops; the equivalent of roughly 10 percent of the U.S. Army's combat force would be unavailable for duty if a crisis suddenly erupted elsewhere in the world.


NATO's strategy in and prosecution of the air campaign in Operation Allied Force left much to be desired. The Kosovar Albanians paid a heavy price in blood for NATO's miscalculations and mistakes. The shortcomings of this operation and the other strategically dubious military interventions in Somalia, Haiti, and Bosnia highlight the way the Clinton Administration generally conceives and manages foreign and national security affairs. Clearly, the United States needs a sharper and more persuasive definition not only of the national interest, but also of the conditions under which it should commit combat troops to defend those interests.

After the war, President Clinton tentatively articulated a wider principle from the Kosovo crisis, asserting:

while there may well be a great deal of ethnic and religious conflict in the world...whether within or beyond the borders of a country, if the world community has the power to stop it, we ought to stop genocide and ethnic cleansing.16

This loose formulation prompted some commentators to proclaim it a "Clinton Doctrine."

Such conclusions appear premature. Indeed, Madeleine Albright, the President's own Secretary of State, cautions against drawing any elastic interpretations from the war in Kosovo. On June 28, she asserted:

Some hope, and others fear, that Kosovo will be a precedent for similar interventions around the globe. I would caution against any such sweeping conclusions. Every circumstance is unique. Decisions on the use of force will be made by any President on a case-by-case basis after weighing a host of factors.17

Secretary Albright's formulation also is problematic; it reduces intervention decisions to improvisation, as happened with the decision to embark on Operation Allied Force. The lessons of Operation Allied Force suggest a better, more principled way to think about military intervention: U.S. military force should be committed only when vital national interests are threatened; but once this occurs, the U.S. armed forces should be free to use whatever force is necessary to win quickly and decisively.

The worst way for the United States to fight wars is to commit forces without a well-developed plan, to devise war aims only after the fighting has begun, and to apply force gradually and half-heartedly to achieve vague political objectives with political leaders' micromanaging military operations. This strategy led to disaster in Vietnam and exacerbated a humanitarian crisis in Kosovo. Before policymakers conclude that the method of fighting the war in Kosovo was successful--and thus should serve as a model for use in future wars--they should study the lessons of Kosovo again. Whether the United States will repeat the costly errors of Vietnam and Kosovo will depend on whether policymakers learn the proper lessons from Operation Allied Force.

James Phillips is Director of Administration and James H. Anderson, Ph.D., is a former National Security Analyst in The Kathryn and Shelby Cullom Davis International Studies Center at The Heritage Foundation.


1. From information on the Web site of the U.S. Department of Defense, Directorate for Information Operations and Reports, Statistical Analysis Division, at http://web1.whs.osd.mil/mmid/casualty/table13.htm

2. Steven Kosiak, "After the War: Kosovo Peacekeeping Operations Could Cost U.S. $2-3.5 Billion a Year," Center for Strategic and Budgetary Assessments, June 7, 1999, p. 1.

3. John Broder, "Clinton Underestimated Serbs, He Acknowledges," The New York Times, June 26, 1999, p. A6.

4. Alexander Nicoll, "The Lingering Question," Financial Times (London), July 1, 1999, p. 11.

5. Matthew Kaminski and John Reed, "KLA Played Key Role in Allied Air War," The Wall Street Journal, July 6, 1999, p. A11.

6. James H. Anderson, Ph.D., and James Phillips, "The Kosovo Liberation Army and the Future of Kosovo," Heritage Foundation Backgrounder No. 1280, May 13, 1999.

7. Joseph S. Nye, Jr., "Redefining the National Interest," Foreign Affairs (July/August 1999), p. 23.

8. For an assessment of the Clinton Administration's changing objectives, see Jack Spencer, "Catalogue of Confusion: The Clinton Administration's War Aims in Kosovo," Heritage Foundation Backgrounder No. 1281, May 13, 1999.

9. For a discussion of U.S. strategic interests in Europe, see Kim R. Holmes and Thomas G. Moore, eds., Restoring American Leadership: A U.S. Foreign and Defense Policy Blueprint (Washington, D.C.: The Heritage Foundation, 1996), p. 15.

10. See John Hillen, "American Military Intervention: A User's Guide," Heritage Foundation Backgrounder No. 1079, May 2, 1996.

11. Peacekeeping deployments often retard the creation of a durable peace. See Edward Luttwak, "Letting Wars Burn," Foreign Affairs (July/August 1999), pp. 36-44.

12. President Bill Clinton, Address to the American Federation of State, County, and Municipal Employees (AFSCME) Biennial Convention, Washington, D.C., March 23, 1999, at http://www.state.gov/www/policy_remarks/1999/990323_clinton_afscme.html

13. The G-8 countries are Canada, France, Germany, Italy, Japan, Russia, Great Britain, and the United States.

14. Associated Press, "Text of the Statement on Kosovo from the G-8 Foreign Ministers," May 6, 1999.

15. For examples of political micromanaging, see Michael R. Gordon with Eric Schmitt, "Crisis in the Balkans: Military Strategy; Pentagon Withholds Copters from Battlefields in Kosovo," The New York Times, May 16, 1999, p. A1; and William M. Arkin, "Objective: Kosovo; Inside the Air Force, Officers Are Frustrated About the Air War," The Washington Post, April 25, 1999, p. B1.

16. Interview of President Clinton by Wolf Blitzer, CNN Late Edition, June 20, 1999.

17. Madeleine Albright, Secretary of State, in remarks to the Council on Foreign Relations in New York, N.Y., June 28, 1999.


James Phillips

Senior Research Fellow, Douglas and Sarah Allison Center

James Anderson

Visiting Fellow