Arbitration Commission of the Peace Conference on Yugoslavia
On 20 November 1991 Lord Carrington asked: "Can the internal boundaries between Croatia and Serbia and between Bosnia and Herzegovina and Serbia be regarded as frontiers in terms of public international law?" Applying the principle of "uti possidetis juris", the commission concluded on 11 January 1992, "The boundaries between Croatia and Serbia, between Bosnia and Herzegovina and Serbia, and possibly other adjacent independent states may not be altered except by agreement freely arrived at... Except where otherwise agreed, the former boundaries become frontiers protected by international law".
Vukovar massacre
In 1990, ethnic tensions between Serbs and Croats worsened after the electoral defeat of the government of the Socialist Republic of Croatia by the Croatian Democratic Union ( – HDZ). The Yugoslav People's Army ( – JNA) confiscated Croatia's Territorial Defence ( – TO) weapons to minimize resistance. On 17 August, the tensions escalated into an open revolt of the Croatian Serbs. The rebellion was centred on the predominantly Serb-populated areas of the Dalmatian hinterland around Knin, approximately north-east of Split, as well as parts of Lika, Kordun, Banovina and eastern Slavonia. In January 1991, Serbia, supported by Montenegro and Serbia's provinces of Vojvodina and Kosovo, unsuccessfully tried to obtain the Yugoslav Presidency's approval for a JNA operation to disarm Croatia's security forces. The request was denied, and a bloodless skirmish between Serb insurgents and the Croatian special police occurred that March. This prompted the JNA itself to ask the Federal Presidency to grant it wartime authority and declare a state of emergency. Even though the request was backed by Serbia and its allies, on 15 March, the Federal Presidency declined. Serbian President Slobodan Milošević, preferring a campaign to expand Serbia rather than to preserve Yugoslavia with Croatia as a federal unit, publicly threatened to replace the JNA with a Serbian army and declared that he no longer recognized the authority of the Federal Presidency. As the JNA came under Milošević's control, the JNA abandoned its plans to preserve Yugoslavia in favour of expanding Serbia. The first casualties of the conflict occurred by the end of March. In early April, the leaders of the Serb revolt in Croatia declared their intention to unite the areas under their control with Serbia. These areas came to be viewed as breakaway regions by the Government of Croatia.