Formally known as the Timor Sea Treaty between the Government of East Timor and the Government of Australia was signed between Australia and East Timor in Dili, Timor-Leste on 20 May 2002, the day Timor-Lesteor attained its independence from United Nations rule, for joint petroleum exploration of the Timor Sea by the two countries. The signatories of the treaty were then Australian prime minister John Howard and his East Timorese counterpart at that time Mari Alkatiri.
The treaty entered into force on 2 April 2003, following an exchange of diplomatic notes and was backdated to 20 May 2002. The treaty was to run for 30 years from the day it came into force or when a seabed boundary could be established, whichever came earlier. However, the subsequent signing of the Treaty on Certain Maritime Arrangements in the Timor Sea (CMATS) in 2007, the period of validity for the Timor Sea Treaty was extended to 2057, when the validity of CMATS also ends.