Operation Trikora was an Indonesian military operation which aimed to seize and annex the Dutch overseas territory of Netherlands New Guinea in 1961 and 1962. After negotiations, the Netherlands signed the New York Agreement with Indonesia on 15 August 1962, relinquishing control of Western New Guinea to the United Nations. Background When the rest of the Dutch East Indies became fully independent as Indonesia in December 1949, the Dutch retained sovereignty over the western part of the island of New Guinea and took steps to prepare it for independence as a separate country. The Dutch and some West Papuan leaders argued that the territory did not belong to Indonesia because the West Papuans were ethnically and geographically separated from Indonesians, had always been administrated separately, and that the West Papuans did not want to be under Indonesian control. From its independence in 1949 until 1961, Indonesia attempted to gain control of Western New Guinea through the United Nations without success. Since the Indonesian National Revolution, Indonesian nationalists had regarded Western New Guinea as an intrinsic part of the Indonesian state. They also contended that Western New Guinea (Irian Barat) belonged to Indonesia and was being illegally occupied by the Dutch. Since 1954, Indonesia had sporadically launched military raids into Western New Guinea. Following the failure of negotiations at the United Nations, the president of Indonesia, Sukarno, escalated pressure on the Netherlands by nationalising Dutch-owned businesses and estates and repatriating Dutch nationals. These actions increased tensions between Indonesia and the Netherlands led to a sharp reduction in trade between the two countries. Following a sustained period of harassment of Dutch diplomats in Indonesia, Indonesia formally severed ties with the Netherlands in August 1960. Indonesia also increased its military pressure on Dutch New Guinea by purchasing weapons from the Soviet Union and the Eastern Bloc. Over the following years, the Sukarno government would become dependent on Soviet military support. On 19 December 1961, Sukarno decreed the establishment of the People's Triple Command or Tri Komando Rakyat (Trikora) in order to annex what Indonesia called West Irian by 1 January 1963. Trikora's operational command was to be called the Mandala Command for the Liberation of West Irian (Komando Mandala Pembebasan Irian Barat) with Major-General Suharto (the future President of Indonesia) serving as its commander. In preparation for the planned invasion, the Mandala command began making land, air, and sea incursions into West Irian.