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
The political situation in the area did not change until 1995. That year, Croatia militarily defeated the Croatian Serbs in offensives codenamed Flash and Storm, in May and August respectively. That left eastern Slavonia as the last remaining Croatian Serb-held area. Gradual restoration of the area to Croatian rule was agreed upon in November through the Erdut Agreement, and the United Nations Transitional Administration for Eastern Slavonia, Baranja and Western Sirmium (UNTAES) peacekeeping mission was deployed to implement the agreement.