After the killing of six army generals on 1 October 1965, blamed by the army on the PKI, Indonesian military units and allied civilian militias carried out a campaign of killings and mass arrests that ran through 1966 and was concentrated in Central and East Java, Bali and North Sumatra. Human Rights Watch and Amnesty International both place the death toll at between 500,000 and one million, while several hundred thousand more were imprisoned without trial, some for over a decade, including at the Buru Island penal colony; the government declared its phased release of untried 'B-category' detainees complete with a final release of 105 prisoners on 20 December 1979, though Amnesty International disputed that the problem was resolved and released prisoners remained under restrictions. Indonesia's national human rights commission, Komnas HAM, concluded in 2012 that there was sufficient preliminary evidence of gross violations amounting to crimes against humanity, listing killing, extermination, enslavement, forced eviction, arbitrary detention, torture, sexual violence, persecution and enforced disappearance; the government rejected the findings and no prosecutions have followed. A non-binding International People's Tribunal in The Hague reached a similar conclusion in 2016. Indonesian state accounts have long characterised the events as a spontaneous popular response to an attempted communist coup rather than an organised military campaign.
The Indonesian army under Major General Suharto, working with civilian militias and religious youth groups, killed and imprisoned alleged members and sympathisers of the Indonesian Communist Party (PKI)
UN Population Division estimates put Indonesia at about 104 million in 1965. The targeted group was defined by association with the PKI, which claimed roughly 3 million members and up to 20 million in affiliated mass organisations. Estimates of those killed range from 500,000 to over a million; between 600,000 and 750,000 were detained without trial, of whom about 10,000 were held on Buru island for a decade.
The 500,000 lower bound and one million upper bound are used by both Human Rights Watch and Amnesty International and derive from differing extrapolations from regional army and journalistic estimates; no state body has ever produced an official count, and the absence of exhumations and archival access keeps the range wide.
These forms are those listed by Komnas HAM in its 2012 inquiry statement and echoed by Amnesty International and the 2016 International People's Tribunal.
Indonesia