The United Nations Transitional Administration in East Timor (UNTAET),, was a United Nations mission in East Timor that aimed to solve the decades long East Timorese crisis in the area occupied by Indonesian military. UNTAET provided an interim civil administration and a peacekeeping mission in the territory of East Timor, from its establishment on 25 October 1999, until its independence on 20 May 2002, following the outcome of the East Timor Special Autonomy Referendum. The transitional administration was established by United Nations Security Council Resolution 1272 in 1999.

East Timor, also known as Timor-Leste, officially the Democratic Republic of Timor-Leste, is a country in Southeast Asia. It comprises the eastern half of the island of Timor - of which the western half is administered by Indonesia - the exclave of Oecusse on the island's north-western half, and the minor islands of Atauro and Jaco. Australia is the country's southern neighbour, separated by the Timor Sea. The country's size is 14,950 square kilometres (5,770 sq mi). Dili, on the north coast of Timor, is its capital and largest city.