The rise in influence and the increasing militancy of the Communist Party of Indonesia (PKI), and Sukarno's support of it, was a source of serious concern for Muslims and the military, and tension grew steadily in the early and mid-1960s.

"[45] He said at a Non-Aligned Movement summit meeting in Cairo in October 1964 that his current purpose was to drive all of Indonesian politics to the left and thereby to neutralise the "reactionary" elements in the Army that could be dangerous for the revolution.

[53] The initial deaths occurred during organised clashes between the Army and the PKI, including some Indonesian armed forces and police units who were sympathetic to communism and were resisting General Suharto's crackdown.

[54] In early October, forces of the Strategic Command (Suharto's Kostrad) and the RPKAD para-commandos led by Colonel Sarwo Edhie Wibowo were sent to Central Java, a region with strong PKI support, while Army servicemen whose loyalty was uncertain were ordered to be discharged from the ranks.

Armed with wide-bladed knives called parangs, Moslem bands crept at night into the homes of communists, killing entire families and burying their bodies in shallow graves ...

[67] The balance of power was shifted in favour of anti-communists in December 1965, when personnel from both the Army Para-commando Regiment and 5th Brawijaya Military Region units arrived in Bali after having carried out killings in Java.

Charles A. Coppel is sharply critical of this characterisation, in which he sees a western media and academics unwilling to face the consequences of an anti-communist agenda that they endorsed,[106] instead scapegoating Indonesian racism and indulging in extravagant and false claims of hundreds of thousands or millions of Chinese killed.

[115] There were few Western journalists or academics in Indonesia at the time; the military was one of the few sources of information, travel was difficult and dangerous, and the regime that approved and oversaw the killings remained in power for three decades.

A New York Times journalist wrote an article titled "When a Nation Runs Amok" explaining that the killings were hardly surprising since they occurred in "violent Asia, where life is cheap.

"[147] The killings perhaps provided a justification for the Cultural Revolution in China, as Chinese communist leaders were fearful that "hidden bourgeois elements" could infiltrate or destroy leftist movements and organisations, and it was built around this narrative.

The U.S. government and the rest of the Western Bloc had the goal of halting the spread of communism and bringing countries into its sphere of influence; the eradication of the PKI and Suharto's taking power would be a major turning point in the Cold War.

[150] Robert J. Martens, political officer at the U.S. Embassy in Jakarta from 1963 to 1966, told journalist Kathy Kadane in 1990 that he led a group of State Department and CIA officials who drew up the lists of roughly 5,000 Communist Party operatives, which he provided to an Army intermediary.

"[153] Scholars have also corroborated the claim that U.S. Embassy officials provided lists of communists to Suharto's forces, who, according to Mark Aarons, "ensured that those so named were eliminated in the mass killing operations.

"[39][36][40][154] Geoffrey B. Robinson asserts that U.S. government officials, among them Marshall Green, "published memoirs and articles that sought to divert attention from any possible U.S. role, while questioning the integrity and political loyalties of scholars who disagreed with them.

[22]: 156 Robert Cribb, writing in 2002, claims "there is considerable evidence that the U.S. encouraged the killings, by both providing funds to anti-communist forces and supplying the Indonesian Army with the names of people whom it believed were PKI members.

[4]: 179, 204  U.S. President Lyndon B. Johnson's National Security Advisor McGeorge Bundy reported to the president that the events since 1 October had been "a striking vindication of U.S. policy towards Indonesia in recent years: a policy of keeping our hand in the game for the long-term stakes despite recurrent pressure to pull out" and that it was made clear to the Indonesian Army via U.S. Embassy's deputy chief of mission, Francis Joseph Galbraith, that "Embassy and the USG generally sympathetic with and admiring of what Army doing.

"[40][4]: 183  The primary concerns of U.S. officials by December 1965 were that Sukarno had yet to be removed and that plans to nationalise U.S. oil companies had yet to be reversed and warned the emerging Indonesian leadership that Washington would withhold support if threats to U.S. investments were not halted.

According to a report by an Indonesian refugee in Japan, from early December 1965, Indonesia signed "a contract with Sweden for an emergency purchase of $10,000,000 worth of small arms and ammunition to be used for annihilating elements of the PKI."

"[165][166] Declassified documents released by the U.S. Embassy in Jakarta in October 2017 show that the U.S. government had detailed knowledge of the massacres from the start and specifically refer to mass killings ordered by Suharto.

The documents also reveal that the U.S. government actively encouraged and facilitated the Indonesian Army's massacres to further its geopolitical interests in the region and that U.S. officials and diplomats at the embassy kept detailed records of which PKI leaders were being killed.

[10][167] U.S. officials, dismayed at Indonesia's shift towards the left, were "ecstatic" over the seizure of power by right-wing generals who proceeded to exterminate the PKI, and were determined to avoid doing anything that might thwart the efforts of the Indonesian Army.

On 21 December 1965, the Embassy's first secretary, Mary Vance Trent, sent a cable to the State Department which provided an estimate of 100,000 people killed, and referred to the events as a "fantastic switch which has occurred over 10 short weeks.

[178] Given U.S. foreign policy goals of stopping the spread of communism and bringing nations into its sphere of influence, the bloody purge which decimated the PKI, the third-largest Communist Party in the world at the time, was considered a huge victory.

He also states that the U.S. did not simply "stand by" and allow the killings to happen, claiming that "it's easy for American commentators to fall into that approach, but the U.S. was part and parcel of the operation, strategising with the Indonesian Army and encouraging them to go after the PKI.

It was formally established in 2014 by human rights activists, academics, and Indonesian exiles in response to an "absence of an official domestic process of transitional justice based on truth finding.

"[12] In July 2016, chief judge Zak Yacoob publicly read the tribunal's findings, which called the state of Indonesia directly responsible for the events and guilty of crimes against humanity, blamed Suharto for spreading false propaganda and laying the grounds for the massacres, and concluded that the massacres "intended to annihilate a section of the population and could be categorised as genocide";[182] the report also highlighted other allegations which the panel found to be well-founded, including enslavement in labour camps, ruthless torture, systematic sexual violence, and forced disappearance.

Ahmad Tohari's trilogy novel The Dancer (Ronggeng Dukuh Paruk) depicts a village community caught in a revolution, giving readers a perspective less acknowledged in the more popular account of the massacres.

By having its two main characters, Srintil and Rasus, on opposite ends of the revolution, the novel sketches not only the circumstances that could have drawn the greater rural public into communist practices but also the mindset of the people who were tasked with carrying out the killings.

The stillness of the nights was broken by the sounds of the heavy footfalls of boots and the occasional reports of gunshots.Eka Kurniawan's Beauty is a Wound (2002) weaves history into satire, tragedy and the supernatural to depict the state of the nation before, during and after 1965.

The Jakarta Method (2020) by Vincent Bevins builds upon his writing for The Washington Post employing recently declassified records, archival probes, and primary eye-witness interviews gathered from one dozen countries to further examine and bring to greater public acknowledgement of the legacy of the killings.