The United Nations Transitional Administration in East Timor (UNTAET) provided an interim civil administration and a peacekeeping mission in the territory of East Timor, from its establishment on October 25, 1999 until its independence on May 20, 2002 following the outcome of the East Timor Special Autonomy Referendum. Security Council Resolution 1272 established the transitional administration in 1999, and its responsibilities included providing a peacekeeping force to maintain security and order; facilitating and coordinating relief assistance to East Timorese; facilitating emergency rehabilitation of physical infrastructure; administering East Timor and creating structures for sustainable governance and the rule of law; and assisting in the drafting of a new constitution and conducting elections. It was led by Brazil's Sergio Vieira de Mello (Special Representative of the Secretary-General for East Timor) and the Philippines's Lieutenant General Jaime de los Santos (Supreme Commander of the United Nations' Peacekeeping Force (PKF)).
A coalition of nations sent troops to support the peace keeping mission. The forces were led by Australia, which provided the largest contingent and the out of theatre base for operations, supported by New Zealand, who sent the second largest contingent, and took responsibility for the more volatile southern half of the main border, France, whose special forces joined the ANZACs on the first day, as well as contingents from Argentina, Brazil, Denmark, Fiji, Ireland, Japan, Malaysia, Russia, Singapore, South Korea, Thailand, the Philippines, Portugal, Sweden, and the United Kingdom. While the United States supported the transition authority, it did so mainly by underwriting contracts to replace destroyed infrastructure and thus avoided a direct military involvement, allowing the ANZAC led force to take the lead. The United States did, however, deploy a contingent of American police officers to serve with the International Police.
UNTAET was established on October 25, 1999 and was abolished on May 20, 2002 with most functions passed to the East Timor government. The military and police forces were transferred to the newly created United Nations Mission of Support to East Timor (UNMISET).
The following month an executive body, the Transitional Cabinet of East Timor, was formed comprising four Timorese members and four international members.
Progress was made in the development of a judicial system with a Prosecutor General's Office and a Defender Service established. District Courts and Court of Appeal were also established.
In September 2000, the Transitional Cabinet approves the establishment of an East Timor Defence Force. The force was formally established in February 2001 and the guerrilla movement FALINTIL was officially disbanded with many of its members joining the new force.
A voter registration process was completed during this period and preparations were made for elections to a Constituent Assembly that would prepare East Timor for independence expected in 2002.
The Constituent Assembly completed work on a draft constitution and this was promulgated in March 2002, the Assembly would serve as the parliament of East Timor following independence.
Presidential elections were held in April in which Xanana Gusmao was elected president of a future independent East Timor.
East Timor became an independent state on May 20 2002.