A diplomatic and military confrontation between Indonesia and Malaysia, which was precipitated by the formation of Malaysia in 1963, which the Indonesian President Sukarno opposed as a ‘neocolonialist’ action on the part of Malaya. Effectively aiming to unite the new Malaysian territories of Sabah and Sarawak with the rest of Borneo under Indonesian rule, he launched a guerrilla war in these areas in April 1963. It served as a catalyst for greater federal unity in Malaysia, whose troops were assisted by British, Australian, and New Zealand contingents. It also led to increased disaffection in the Indonesian army, which contributed to Sukarno's downfall. His successor, Suharto, ended all hostilities.