Lawful or legitimate? The debate over NATO's 1999 intervention

On 24 March 1999 NATO began its air campaign against the Federal Republic of Yugoslavia. For most Kosovo Albanians the intervention was experienced as rescue at the height of the expulsions and killings. For international lawyers it opened one of the most important debates of the late twentieth century: may force be used without Security Council authorization to stop mass atrocities? This article sets out the main arguments without collapsing them into a single answer.

The UN Charter and the absence of authorization

The UN Charter prohibits the use of force against the territorial integrity of a state, with two main exceptions: self-defence and action authorized by the Security Council. The 1998 resolutions on Kosovo — 1160, 1199 and 1203 — demanded an end to violence and cooperation with international missions, but none expressly authorized the use of force [1] [2] [3].

Russia and China opposed military intervention and could block any such resolution by veto. NATO decided to act without one. After the bombing began, a draft resolution demanding that it stop was not adopted by the Security Council [4].

The humanitarian argument

NATO governments justified the campaign by the need to prevent a humanitarian catastrophe, Belgrade's failure to comply with Security Council demands and the collapse of the negotiations at Rambouillet [5] [6]. Supporters of this argument stressed that hundreds of thousands of people had been displaced during 1998 and that Reçak had shown what could happen.

Opponents argued that "humanitarian intervention" was not an accepted legal basis, that it could be abused by powerful states, and that the bombing was accompanied by an escalation of violence on the ground. This last argument calls for precision: human-rights documentation shows that the mass expulsions and killings were carried out by Serbian and Yugoslav forces, and the ICTY attributed criminal responsibility to the persons convicted in the Šainović et al. case [7] [8].

The independent commission: "illegal but legitimate"

The Independent International Commission on Kosovo, which published The Kosovo Report in 2000, proposed a formula that became widely known: the intervention was "illegal but legitimate" — illegal because it lacked Security Council approval, legitimate because it sought to end grave and systematic human-rights violations once diplomatic avenues had been exhausted [9].

The formula did not end the debate. Some lawyers argued that a new customary norm permitting intervention in extreme cases was emerging; others warned that separating legality from legitimacy weakens the international legal order. In the years after Kosovo the discussion influenced the development of the idea of a "responsibility to protect".

Civilian harm and proportionality

The legitimacy of an intervention is judged not only by its purpose but also by how it is conducted. Human Rights Watch documented incidents in which NATO bombing killed civilians and concluded that between 489 and 528 civilians were killed in ninety separate incidents [10]. Among the incidents discussed were the strikes of 14 April 1999 on columns of displaced people on the Gjakovë–Deçan road, which according to the report killed seventy-three civilians, and strikes on civilian facilities in Serbian cities.

The civilian victims of the bombing are part of the history of the war and must not be hidden to protect the narrative of liberation. Nor should they be used to relativize the documented crimes against the Albanian population. Both can and must be assessed on the evidence.

The ICTY Prosecutor's review

The ICTY had jurisdiction over crimes committed on the territory of the former Yugoslavia, including any that might have been committed by NATO forces. The Prosecutor set up a committee to review the air campaign. In its final report of 2000, the committee recommended that no investigation be opened, finding that the law or the evidence was insufficient to justify one for the incidents reviewed [11].

Human-rights organizations criticized the recommendation and its reasoning on several incidents. Lawyers regard the report as an important precedent — whether as an example of independent review or as an example of the limits of international justice when powerful actors are involved.

What ended the war?

Why Belgrade accepted the terms in early June 1999 has been answered in different ways. Some scholars emphasize the cumulative effect of the bombing on infrastructure and the economy; others, diplomatic isolation after Russia's change of position and the joint mediation mission; still others, the increasingly credible threat of a ground operation [6].

A separate debate concerns the role of the KLA. According to some analyses, the fighting on the border with Albania, as at Koshare and Pashtrik, forced Yugoslav forces to concentrate and become more visible from the air; other scholars regard the KLA's military role in this phase as secondary to NATO pressure [12] [6]. The archive presents these interpretations side by side.

Resolution 1244: legitimation after the fact?

After the Military Technical Agreement of 9 June, the Security Council adopted Resolution 1244 on 10 June 1999, authorizing an international civil and security presence in Kosovo [13] [14]. Some authors have read this as political acceptance of the intervention's outcome; others stress that the resolution did not retroactively make the air campaign lawful.

For Kosovo's history, Resolution 1244 matters in two ways: it ended the war and created the framework of international administration, but it left the final status open — a question that would shape the following decade.