NATO

Operation Allied Force

The campaign began on the evening of 24 March 1999, after the failure of the Rambouillet and Paris talks and the withdrawal of the OSCE verifiers. Strikes hit military and security targets in Serbia, Kosovo and Montenegro and, as the weeks passed, dual-use infrastructure such as bridges, refineries and power facilities. The operation was conducted essentially from the air; NATO did not deploy ground combat forces in Kosovo during the campaign.[1][2]

In April 1999 the allies set out their conditions for ending the bombing: a verifiable end to military action and violence; the withdrawal of military, police and paramilitary forces from Kosovo; an international military presence; the safe return of refugees and displaced persons; and a political framework based on the Rambouillet accords. These conditions were later reflected in the plan the Yugoslav leadership accepted in June.[1][3]

Legality and legitimacy

The Security Council did not adopt a resolution explicitly authorizing the use of force, because Russia and China opposed such a step. NATO governments justified the intervention by the need to avert a humanitarian catastrophe and by Belgrade's failure to comply with the demands of Resolutions 1199 and 1203. Critics, including many international lawyers, argued that the intervention breached the UN Charter's prohibition on the use of force.[4][2]

The Independent International Commission on Kosovo concluded that the intervention was illegal, because it lacked the prior approval of the Security Council, but legitimate, because diplomatic avenues had been exhausted and the intervention had the effect of freeing the majority population of Kosovo from long-standing repression. This assessment, often summarized as “illegal but legitimate”, was widely invoked in later debates on humanitarian intervention.[5]

This archive does not issue a legal verdict on the question. It sets out the main arguments, the documents on which they rest, and the distinction between legality under international law and moral and political legitimacy. The positions are compared in a structured way in the research article The legality of the intervention, which also shows which questions remain open in the legal literature.

Civilian victims of the bombing

Human Rights Watch documented incidents in which NATO strikes caused civilian deaths in the Federal Republic of Yugoslavia, including Kosovo. In its 2000 report, the organization concluded that between 489 and 528 civilians were killed in ninety separate incidents, and criticized among other things the use of cluster bombs and strikes on certain dual-use targets. The figure is an estimate by a non-governmental organization, with its own methodology and limitations, and should be cited as such.[6]

Several incidents inside Kosovo became publicly known. On 14 April 1999 NATO aircraft struck a column of displaced Kosovo Albanians on the Gjakovë–Deçan road; after initially contradictory statements, NATO acknowledged that it had hit civilian vehicles. On 19 and 21 May 1999 NATO struck Dubrava prison near Istog, where many Albanian prisoners were held. What followed these strikes is the subject of differing accounts and is treated separately in the event record.[6][7]

The ICTY Prosecutor's review

Following complaints and public calls for an investigation, the Prosecutor of the International Criminal Tribunal for the former Yugoslavia set up a committee to examine whether NATO's campaign provided grounds for a criminal investigation. Its final report, published in June 2000, examined among other things the strike on the convoy near Gjakovë, the bombing of the Serbian state broadcaster's building in Belgrade and the use of cluster munitions, and recommended that no investigation be opened.[8]

The Office of the Prosecutor accepted the recommendation. Some human-rights organizations and lawyers criticized the conclusion, particularly regarding strikes on dual-use civilian objects. For the reader, the distinction matters: a decision not to open an investigation is not a court judgment and establishes neither the guilt nor the innocence of any person; it reflects the prosecution's assessment, at the time, of the possible grounds for an investigation.[8]

Bombing and mass expulsions: what is established and what is debated

After 24 March 1999, the expulsions of Albanians from Kosovo escalated rapidly. According to UNHCR, by 9 June 1999 some 863,000 refugees were outside Kosovo, while the ICTY found that at least 700,000 Kosovo Albanians were displaced during this period. In the Šainović et al. case, the tribunal found that the forces of the Federal Republic of Yugoslavia and Serbia conducted a deliberate campaign of deportation and forcible transfer of the Albanian population; the convictions for these crimes were upheld on appeal.[9][7][10]

During the war, the Yugoslav authorities claimed that people were fleeing NATO bombs or fighting with the KLA. The ICTY trial chamber did not accept this as the principal cause of the mass departures, linking them instead to deliberate actions by Yugoslav and Serbian forces. This finding concerns the responsibility of the accused in that case and should be read within its limits.[9]

The historiographical debate concerns a different question: whether the intervention accelerated the expulsion campaign, or whether such a campaign had been planned and would have happened regardless. Some scholars argue that the start of the bombing gave Belgrade the time and pretext to carry it out; others stress that violence against civilians and mass displacement were already documented in 1998. The existence of a plan called “Horseshoe”, made public by the German government in April 1999, remains disputed among researchers.[2][11]

The end of the campaign and the entry of KFOR

After the Ahtisaari–Chernomyrdin plan was accepted on 3 June and the Military Technical Agreement was signed in Kumanovo on 9 June, NATO suspended air strikes on 10 June 1999. The same day the Security Council adopted Resolution 1244. KFOR began entering Kosovo on 12 June; that same day a Russian unit reached Pristina airport, triggering a brief diplomatic crisis between the allies and Moscow.[12][3][2]

The withdrawal of Serbian and Yugoslav forces was completed on 20 June 1999, and NATO formally declared the air campaign over. The rapid return of Albanian refugees was accompanied by a new period of violence, documented by the OSCE, against Serbs, Roma and members of other communities, as well as against Albanians perceived as political opponents. These events belong to the postwar period and are covered in the corresponding chapter, clearly separated from the war of 1998–1999.[13]