As the campaign for the 2020 Democratic nomination for president heats up, a key foreign policy question is whether and under what conditions candidates support the use of military force. Given the debacles in Iraq, Afghanistan and Libya over the past 15 years, it is hard to imagine any Democrat who wants to secure the nomination being eager to talk about the need for military intervention except under extremely narrow circumstances.

Twenty years ago, President Bill Clinton led NATO on a 78-day bombing campaign in southeastern Europe. He did so without U.N. Security Council authorization because he knew that Russia and China, both permanent members of the Security Council, would oppose a mission designed to protect a minority population — the Kosovar Albanians — from the threat posed by the government of Serbia, headed by Slobodan Milošević.

It was the height of America’s “unipolar moment,” a time when the United States had no doubt that its awesome military power could right wrongs in the world. Bombing from 15,000 feet, the United States suffered no military casualties. Russia was furious that the West was attacking a fellow Slavic nation. China grew apoplectic when its embassy in Belgrade was bombed due to what the Clinton administration claimed were faulty maps. However, the reactions of those two powers were largely irrelevant to U.S. decision-making.

Two decades later, it is hard to imagine a U.S. president, and certainly a Democratic president, using this level of force for humanitarian purposes, particularly without authorization from the United Nations. Nor would there be cries from Europeans to act, as there were in 2011 when the British and French pushed for the intervention in Libya. But the Kosovo War raises interesting questions for candidates running for president: Should the United States and its NATO allies have acted 20 years ago to prevent what may have been another act of genocide committed by Milošević? Would they simply stand by today under similar circumstances given current attitudes toward military intervention?

Assessing Operation Allied Force

The U.S.-led NATO operation, Allied Force, cannot be assessed in isolation from the wars that occurred on the territory of the former Yugoslavia in the early 1990s, as well as the failures of the international community to act in preventing genocides in Srebrenica and Rwanda after the end of the Cold War. Just four years before the Kosovo intervention, the Clinton administration was jubilant after brokering a peace agreement in Dayton, Ohio, ending the nearly four-year war in Bosnia-Herzegovina. This was by no means an easy feat, and it came only after the largest act of mass killing in Europe since World War II. However, while the Dayton Peace Agreement was successful in terminating the carnage in Bosnia, it failed in keeping a check on Milošević and his repression of Kosovar Albanians.

In recognizing the ethnically cleansed Republika Srpska (i.e. the Serb Republic in Bosnia), the Dayton Accords sent the wrong signal to many Albanians in Kosovo who had by that point been pursuing a campaign of non-violent resistance. Following Dayton, it seemed that an armed conflict would encourage the international community to intervene and resolve the situation sooner — creating what some have termed the moral hazard of humanitarian intervention. In addition, by the end of 1996, the West was in a partial rapprochement with the Federal Republic of Yugoslavia led by Milošević, resulting in the normalization of diplomatic relations and lifting of trade sanctions. Yet, this was despite the fact that the government’s treatment of Kosovar Albanians continued to worsen, and there was no indication Kosovo’s autonomy, which Milošević revoked in 1989, would be re-established. In short, the stage was set for the intensification of the Serb-Albanian conflict. By February 1998, Kosovo was embroiled in a full-scale civil war.

For almost a year, the international community tried to deter Milošević’s regime from attacking the Albanian civilian population in Kosovo by imposing a range of trade and investment sanctions, asset freezes and arms and oil embargos. All of these were in vain and some even outright counterproductive, as in the case of an arms embargo on the significantly weaker Kosovar Albanian forces. As the human rights violations, large-scale displacement and death counts began to soar, and the international attempts at mediation failed, it became clear direct military intervention remained as the last resort. Yet, it was only after the first mass graves of Albanian civilians were uncovered and massacres continued in January 1999 that U.S. Secretary of State Madeleine Albright announced that diplomacy combined with a credible threat of force would be the American strategy moving forward.

The International Contact Group, which included the United States, the United Kingdom, France, Russia, Germany, and Italy, made one final push to mediate the conflict in early February at the Rambouillet conference. The peace process ultimately failed as Milošević refused to concede to any of the terms that would see greater autonomy for Kosovo. As the Yugoslav military campaign appeared to target the civilian population in a manner reminiscent of the ethnic cleansing in Bosnia-Herzegovina, NATO acted based on the doctrine of humanitarian intervention and launched its Operation Allied Force on March 24, 1999.

That same day, U.N. Secretary General Kofi Annan, while arguing that the Security Council “should be involved in any decision to resort to the use of force,” also stated, “It is indeed tragic that diplomacy has failed, but there are times when the use of force may be legitimate in the pursuit of peace.” A month later, British Prime Minister Tony Blair, speaking in Chicago, justified the war to his American audience by saying “those nations which have the power, have the responsibility.”

Was the Use of Force Necessary?

The debate over whether NATO was right to resort to the use of force after having failed to obtain a U.N. Security Council resolution which would authorize such action continues to provide plenty of fodder for international law scholars and students. Yet, given Milošević’s record until that point, the ineffectiveness of sanctions and the inability to reach a peace agreement through international mediation, there was little left on the menu of workable options. Kosovo was, in a way, the opportunity for the West to atone for its failure to prevent the genocides of the mid-1990s.

It set a precedent, however, for U.S. action regardless of support from the U.N. Security Council, and only four years later, the George W. Bush administration launched an attack with a “coalition of the willing” against Iraq for its alleged failure to give up weapons of mass destruction, in that instance ignoring not just Russian opposition but that from allies like France and Germany as well. And when Vladimir Putin decided to invade Ukraine in 2014 and annex Crimea, he could point to the Kosovo intervention to argue he was simply acting on similar grounds to protect the Russian-speaking population next door.

Ten years ago, it would have been easier to make the case that the war was justified because Serbia looked to be on a surer path toward integration with Europe, and Kosovo was just celebrating its first anniversary as an independent state. The hope that existed then for both countries has largely evaporated. But the Kosovo War is also a reminder that post-conflict assistance is critical, and the European Union, which should have done much more to sanction corruption and democratic backsliding, as well as to offer a clearer pathway for the integration of the Western Balkans, instead largely turned a blind eye to the situation and kept its fingers crossed that everything would work out.

Back to the 2020 Presidential Race

In his Chicago speech in April 1999, Blair declared, “Twenty years ago we would not have been fighting in Kosovo. We would have turned our backs on it.” Is the same true twenty years later after America’s experiences with the use of force in the intervening years? It’s a question worth asking of candidates for whom criticism of the wars in Iraq, Afghanistan and Libya comes easy. But a progressive foreign policy must have a place for the protection of human rights. And if the United States is going to be understandably more reluctant to use force than it was at the height of its power in 1999, what policies will it craft to help protect vulnerable populations, not just at home, but abroad?

Professor James Goldgeier is a Visiting Senior Fellow at the Council on Foreign Relations and professor of international relations at the School of International Service at American University, where he served as dean from 2011 to 2017. He holds the 2018-19 Library of Congress U.S.-Russia Chair at the John W. Kluge Center. You can follow him on Twitter @JimGoldgeier.

Dr. Gorana Grgic is a jointly appointed Lecturer at the Department of Government and International Relations and the United States Studies Centre at the University of Sydney, Australia. She is currently a Visiting Fellow at the Harvard Minda de Gunzburg Center for European Studies. You can follow her on Twitter @GoranaGrgic.

A F-16 Fighting Falcon flies over Aviano Air Base, Italy, as it departs for an NATO Operation Allied Force mission in the Balkans March 27, 1999. (U.S. Air Force photo/Senior Airman Mitch Fuqua)