The area had been granted special status by the government in 1959, allowing Islamic traditions and laws greater prominence. Centralizing tendencies of the government of Suharto led GAM to begin its campaign in the 1970s, issuing a declaration of independence and self-determination in 1976. The main perceived threats were to Acehnese religion and culture from the "neo-colonial" government and the rising numbers of Javanesenese migrants. The uneven distribution of income from Aceh's substantial natural resources was another point of contention. Despite these problems GAM does not have the support of the majority of the Acehnese people, if election results can be trusted.
At first the guerilla war of GAM was almost entirely unsuccessful, and the government appeared to have entirely neutralised the group by 1977. The group renewed its activities in the 1980s, apparently with financial support from Libya and Iran, fielding around 3,500 soldiers. Although it failed to gain widespread support, the group's actions led the government to institute repressive measures, which aided GAM by alienating the civilian population. The area was given "Operational Military" status from 1991 to 1995. Negotiations between the two sides, although improved by the toppling of Suharto, were endlessly broken off, and both the military and GAM were often accused of human rights abuses.
In 1996 the Indonesian government announced the end of GAM. The TNI presence in the region was not greatly reduced and reports of arrests, torture, and extra-judicial killings continued. In 1999 a troop withdrawal was announced, but the military presence remains high and troop numbers are believed to have risen during the rule of Megawati Sukarnoputri to around 35,000 by mid-2002. Security crackdowns in 2001 and 2002 resulted in several thousand civilian deaths.
The leader of GAM, Hasan di Tiro, and his chief deputy, Zaini Abdullah, both reside in exile in Sweden. The group's main Indonesian spokesman is Abdullah Syafei'i Dimatang.
In 1999 it was reported that the group had split into two factions, ASNLF (representing the original group) and the Free Aceh Movement Government Council (MP-GAM). This has been denied by GAM spokespersons but widely reported by the Indonesian media.
Other Aceh separatist groups exist, and there is some tension between them and GAM over tactics and GAM's monopoly of negotiations with the government.