The Dutch were established in the west of the island by 1613, with the Portuguese in the north and east. Portugal established a colonial administration in Timor in 1702, but the claim was disputed by the Dutch, as well as by the Timorese, who frequently rebelled. Timor was divided into West and East by treaties of 1859 and 1913 and subjected to Dutch and Portuguese control respectively; during World War II both parts were occupied by Japan. West Timor (capital Kupang) became part of Indonesia in 1949. East Timor (capital Dili), comprising an enclave on the northwest coast and the islands of Atauro and Jaco, was seized by Indonesia in 1975, and became the Indonesian province of Timor Timur the following year. The annexation was not recognized by the UN, and provoked guerrilla warfare by the Fretilin pro-independence group. In August 1999, despite a six-month campaign of Indonesian violence and intimidation, the East Timorese turned out in overwhelming numbers to vote in favour of the referendum on independence. The Indonesian government conceded the following November, and the UN set up a transitional administration. East Timor declared formal independence on 20 May 2002.