Challenges to the unitary state While the issue has become particularly acute since 1998, problems of national cohesion predated Suharto's falL Indonesia's size, cultural diversity and lack of direct pre-colonial antecedents have long forced its leaders to work hard to foster asense of national identity. The question of whether Indonesia should be a unitary or a federal state was central to nationalist debates during the late colonial period. In 1949, the Dutch transferred sovereignty to the federal Republic of the United States of Indonesia (RUSI). The federation included al1 areas of the Netherlands East Indies except West New Guinea (later Irian Jaya, now called Papua), which remained under Dutch controL RUSI survived for just eight months. After an attempted coup against the nationalists' Indonesian Republic, which control1ed large areas of Java and Sumatra, Sukarno proclaimed a new, unitary Republic of Indonesia in August 1950. Some of the states left behind by the Dutch surrendered their powers without a struggle, while others, notably Eastern Indonesia, resisted what they saw as the imposition of Javanese rule, and armed rebellions broke out in South Sulawesi and on Ambon. Although the rebellion on Ambon had been crushed by November 1950, guerrilla warfare continued on nearby Seram until 1963.5 Among radical Muslims in West Java, dissatisfaction was evident from 1948, when the Darul Islam (House of Islam) movement was established, with the objective of a federal Islarnic state. By 1954, Darul Islam's influence extended into Central Java, South Sulawesi and Aceh, and it controlled much of rural West Java until1962, when its leader was captured.