The United Nations Transitional Administration for Eastern Slavonia, Baranja and Western Sirmium (UNTAES) was a UN peacebuilding transitional administration in the Eastern Slavonia, Baranja and Western Syrmia in the eastern parts of Croatia (multicultural Danube river region). The transitional administration lasted between 1996 and 1998. It was also sometimes known as the United Nations Transitional Authority in Eastern Slavonia, Baranja and Western Sirmium. The transitional administration was formally established by the United Nations Security Council Resolution 1037 of January 15, 1996. The transitional administration was envisaged and invited in the November 1995 Erdut Agreement between the Croatian Government and the representatives of the local Serb community in the region. At the time of UNTAES deployment the region already hosted another traditional type UN peacekeeping mission known as the UNCRO. While the region was covered under the UNCRO's sector east (sector led by Russian and Belgian forces), the whole UNCRO mission was brought into question by the Operation Storm escalation of hostilities.
UNTAES is only the third UN peacekeeping mission in history (after UNTEA in Western New Guinea and UNTAC in Cambodia) where the UN assumed direct and high executive powers in the territory of concern. Via UNTAES, the United Nations temporarily took the role of governance in the region by creating an UN protectorate. At the end of the UNTAES deployment an additional monitoring support mission was provided for the region under the name of the United Nations Civilian Police Support Group.
History
Pre-establishment events
After the Operation Storm in mid-1995, the only remaining part of the self-proclaimed proto-state Republic of Serbian Krajina became that in eastern Croatia along the Danube river. Contrary to Krajina mainland, Eastern Slavonia, Baranja and Western Syrmia shared a long border with the Federal Republic of Yugoslavia (its constituent Republic of Serbia). It was also economically and socially dependent and politically much more closely aligned with authorities in Belgrade and Novi Sad than Krajina. This led the international community to believe that Croatian intervention in Eastern Slavonia case would trigger a military reaction from Yugoslavia and result in an escalation of hostilities. At the same time, the military defeat of Krajina and signing of the Washington Agreement opened the space to resolve the armed conflict in Bosnia which the US Administration wanted to use for political benefits before the 1996 United States presidential election.
In the context of successful Croatian military interventions of Bljesak and Oluja, initial idea that the region of Eastern Slavonia will be integrated back to Croatia through the peaceful means was perceived with astonishment on Croatian side and as a form of pressure from the international community. Croatian military establishment held informal talks about preparation of a military solution for the region under the code name "Skok u Dalj" ("Jump to Dalj"). There was lack of enthusiasm and belief that peaceful process will be successful among involved parties and other states in the region, themselves recently involved in Yugoslav Wars.
The Erdut Agreement between the Croatian Government and the representatives of the Serbs in the region was signed in November 1995, which requested that the UN form a transitional authority and a peacekeeping force. United Nations Security Council Resolution 1023 supported that, and after the UNCRO mission was terminated in the United Nations Security Council Resolution 1025, UNTAES was set up to serve as a United Nations protectorate over the region in Resolution 1037. Reintegration of the region, the last part of the country outside the control of central government and arguably geopolitically the most sensitive part of former self-proclaimed Republic of Serbian Krajina, was the most important Croatian condition for participation in Dayton Peace Negotiations. The subsequent Dayton agreement for peace in Bosnia ended the deadliest conflicts of the Yugoslav wars.