Indonesia 1965 Mass Killings: CIA Support for the Anti-Communist Purge

Introduction

On the morning of October 1, 1965, the Indonesian public awoke to news that an attempted coup — attributed by the military to a group calling itself the September 30th Movement — had resulted in the killing of six senior Army generals the previous night. The bodies were found at Lubang Buaya (Crocodile Hole) near Jakarta. General Suharto, then commander of the Army Strategic Reserve Command (KOSTRAD), moved quickly to declare the September 30th Movement a Communist Party of Indonesia (PKI) conspiracy and to assume effective military command.

What followed was one of the largest and most rapid mass killings of the twentieth century. Between October 1965 and March 1966, an estimated 500,000 to one million people were killed across Indonesia — concentrated in Java, Bali, Sumatra, and other islands — in an anti-communist purge executed by the Indonesian military, local militias, and religious organisations mobilised against the PKI. Approximately one million more were imprisoned; many spent decades in detention without trial.

The role of the CIA and the US government in supporting this purge has been substantially documented through declassified materials, particularly the 2017 release from the National Security Archive's Indonesia Documentation Project.

The September 30th Movement: What Actually Happened

The events of September 30, 1965 remain contested by historians. The official Suharto-era account — taught in Indonesian schools for three decades — attributed the killings of the generals to a PKI conspiracy. Alternative analyses — most notably by historian Benedict Anderson and Cornell University's "Cornell Paper" (1966) — raised questions about whether the September 30th Movement was a PKI-directed operation or an internal Army faction conflict in which Suharto himself may have had foreknowledge.

John Roosa's Pretext for Mass Murder (2006) — the most definitive scholarly account — concluded that PKI Central Committee member Sjam Kamaruzaman was involved in the planning of the September 30th Movement, establishing a genuine PKI leadership link, while also demonstrating that the PKI central leadership was largely unaware of the plot. The killings of the generals were real; the attribution of the entire PKI as its orchestrating body was the pretext rather than the documented reality.

Scale of the Killings

The death toll estimates range from 500,000 (a figure long used in standard historical accounts) to over one million, with more recent scholarship suggesting the higher end is more accurate. The killings were geographically widespread and included:

• Mass executions of suspected PKI members, sympathisers, and their families
• Killings of ethnic Chinese Indonesians targeted alongside communist associations
• Detention camps where thousands died of disease and mistreatment
• Forced labour

Robert Cribb's demographic research and Joshua Oppenheimer's documentary evidence — gathered from perpetrators in The Act of Killing (2012) and The Look of Silence (2014) — provide documentation of the scale and methods that supplements the written historical record.

The US Role: What Declassified Documents Show

The 2017 release of declassified State Department and CIA materials through the National Security Archive's Indonesia Documentation Project provides the most detailed public record of US government knowledge and support during the killings. Key documented facts include:

Embassy lists of suspected communists: Declassified cables document that US Embassy officers in Jakarta compiled lists of suspected PKI members — estimated in some cables at up to 5,000 names — and provided them to the Indonesian military. These lists were used to identify and kill individuals. A 1990 interview with Robert Martens, the US Embassy political officer responsible, confirmed that the lists were provided with knowledge of how they would be used.

Active encouragement: Declassified cables show US Embassy officials expressing support for the military's actions and encouraging the Indonesian Army to move quickly against the PKI. A December 1965 cable from US Ambassador Marshall Green characterised the killings as "a gleam of light in Asia."

Arms supply: The US provided communications equipment and other military supplies to the Indonesian Army during the purge period, facilitating operational capacity.

Knowledge of scale: Cables from the period show that US officials were aware of the mass killings as they occurred and did not seek to stop them; the killings were viewed as an acceptable price for the destruction of the PKI — at the time the largest communist party outside the Soviet Union and China.

Bradley Simpson's Scholarship

Bradley Simpson's Economists with Guns: Authoritarian Development and US-Indonesian Relations, 1960–1968 (2008) provides the most comprehensive scholarly examination of the US-Indonesia relationship during this period, drawing on declassified documents from multiple archives. Simpson's analysis establishes that the US had strategic interests in the destruction of the PKI that pre-dated the September 30th Movement, that US officials engaged in active encouragement of the military's actions, and that the relationship between the US and the Suharto military constituted a form of complicity in the killings.

Documentary Record and Scholarly Consensus

The September 30, 1965 coup attempt — which targeted the senior Indonesian Army leadership — was followed within days by a counter-response organised under General Suharto, framing the PKI as responsible. What followed between October 1965 and March 1966 was a mass-killing campaign in which army units, paramilitary groups, and civilian militias killed members and alleged sympathisers of the PKI and affiliated organisations. Credible historical scholarship, including the work of Robert Cribb and Geoffrey Robinson, places the death toll at 500,000 to 1,000,000 people, making it one of the largest political killings of the twentieth century.

The evidentiary record was materially extended by Joshua Oppenheimer's 2012 documentary The Act of Killing, in which perpetrators described and re-enacted their role in the killings on camera, providing primary-source testimony unavailable from official archives. The 2017 declassification of US Embassy cables confirmed that American diplomatic staff possessed detailed knowledge of the killings as they occurred and in some instances provided lists of PKI members to Indonesian military counterparts. The combination of oral testimony, declassified signals intelligence, and demographic reconstruction has produced a scholarly consensus on the fact and scale of the killings that no serious revisionist position disputes.

Distinguishing Confirmed from Overclaimed

The confirmed record establishes:

• CIA and US Embassy provision of lists of suspected PKI members to Indonesian military
• US officials' awareness of and support for the killings
• Material support (communications equipment) during the purge

The overclaim to reject:

• "The CIA directly orchestrated and ran the killings" overstates the documented evidence. The killings were conceived, ordered, and executed by Suharto and the Indonesian military. US support was material and morally significant; it does not make the CIA the operational author of the massacres.

Indonesia's Reckoning

Indonesia has never formally prosecuted those responsible for the 1965-66 killings. A 2012 International People's Tribunal (Tribunal Rakyat) held in The Hague found the killings constituted crimes against humanity and found evidence of US involvement. Indonesian civil society organisations have pressed for official acknowledgment; successive governments have moved slowly or not at all. Joshua Oppenheimer's films contributed to renewed Indonesian public debate about the killings after decades of official suppression under the Suharto-era New Order.

What Would Change Our Verdict

• Declassification of additional CIA operational records from the 1965-66 period
• Indonesian government acknowledgment and truth commission process
• Independent forensic investigations at known mass grave sites

Verdict

Confirmed. The mass killings of 500,000 to one million people following the September 30, 1965 coup attempt are documented historical fact. Declassified US State Department and CIA materials confirm that CIA and US Embassy officers provided lists of suspected PKI members to the Indonesian military, that US officials were aware of and supportive of the killings as they occurred, and that material support was provided. The characterisation of the US as an operational author of the killings overstates the documented record; the characterisation of US complicity is confirmed.