On the morning of September 30, 1965, a small group of army officers and Communist Party of Indonesia (PKI) members attempted a coup against the Indonesian army leadership. Six army generals were killed, but the coup failed and was crushed by surviving army leaders in a few days. Together with other right-wing forces, the army, under the command of Gens. Suharto and Abdul Haris Nasution, retaliated.

Hundreds of thousands of real and suspected communists were massacred, and a new, military-dominated regime under Suharto was installed. Western powers like the US, Britain, and the Netherlands condoned and often actively supported the massacres.

Indonesia’s military junta took control of the media on October 2, using it to spread its own version of the events. In the junta’s version, the killing of the generals was the spark that ignited popular anger against a party that was hated for its violence, its disregard for religion and its lack of patriotism. Supposedly, PKI plans for a violent revolution and elimination of anyone who opposed it were stopped by a wave of spontaneous popular anger against the treacherous communists.

For decades, this version of the mass killings of 1965–66 has been reinforced by state propaganda and parroted by Western experts who saw the “spontaneous” eruption in murderous violence as confirmation of pre-existing racist ideas about fanatical and irrational “orientals.”

Historical research has demolished this version of events. The failed coup was not an initiative of the PKI as a whole, but of a small number of PKI leaders working with sympathetic army officers who wanted to remove several right-wing army leaders — not take state power. The massacre that followed was systematic, organized by right-wing nationalist politicians and militia, religious organizations, and, most of all, the Indonesian army. This coalition for murder received political and material support from Western powers.

Within days of the coup, US and British officials began making plans to exploit the political situation. The coup offered them the chance to crush the PKI, a party that Western officials feared was getting dangerously close to state power.

In the years leading up to the coup, the PKI tried to establish itself as the fiercest anti-imperialist party in the country, mobilizing against the influence of foreign capital, especially of the Dutch and British variety. It supported Indonesian President Sukarno in his demand that the Dutch hand over Irian Jaya (West Papua) to Indonesia and in his campaign against Malaysia, which it denounced as an instrument of British imperialism.

For a time this strategy was successful. In the parliamentary elections of 1955 — the last before Sukarno adopted his authoritarian system of “guided democracy” — the PKI emerged as the country’s fourth largest party with 16.4 percent of the vote. Party membership had grown from less than twenty thousand in 1954 to over 1.5 million. Millions were organized in PKI-allied trade unions and mass organizations of peasants, women, students, and other groups.

It was not just the growth of the PKI that set off alarm bells in the West. In the late 1950s, the US backed right-wing rebellions against Sukarno, but this backfired when the rebels were defeated. American support for his opponents drove Sukarno further away from the Western bloc and damaged US relations with the most powerful force on the Indonesian right: the army.

Meanwhile, the communists’ contribution to the fight against the rebels won them popular sympathy and growing favor from Sukarno. By the early sixties, the PKI was the world largest Communist party outside the Soviet bloc, and Indonesia was the largest non-bloc recipient of Soviet economic and military aid.

After the failure of the regional rebellions, the US adopted a different strategy. With the help of philanthropic foundations like Ford and Rockefeller and institutions like the World Bank, the US restored its relationship with the Indonesian army and the country’s right by providing material assistance and training to Army officers and pro-Western intellectuals.

But the US government’s ability to influence Indonesian state policy ultimately depended on President Sukarno. Sukarno, the historical leader of the Indonesian independence movement, was very popular and essentially ruled by decree. He was not a communist, but he was a fervent anticolonialist who dreamed of a powerful, fully independent Indonesia that would play an important role on the world stage.

Sukarno increasingly clashed with Western powers — especially the UK and US, whom he denounced as neocolonialist. In early 1965, Indonesia withdrew from the United Nations and expelled the World Bank and International Monetary Fund.

As a result, Western officials were pessimistic about their ability to manipulate the political landscape in Indonesia. In early 1965, the Dutch ambassador to Indonesia, E. L. C. Schiff, said in a wire to the minister of foreign affairs that the consensus among his colleagues was that Sukarno would remain the country’s leader until his death and that “it is no longer possible to keep Indonesia from slipping into the left.”

The US had also decided by then that Sukarno could not be pressured to abandon the PKI, and in August 1964 decided to overthrow Sukarno. This decision was in accord with the covert plans of British officials to foment civil war or the collapse of Sukarno’s government.

The UK established a “director of political warfare against Indonesia,” based in Singapore, and the CIA proposed expanding its own operations in Indonesia to include “covert liaison with and support for existing anti-Communist groups, black letter operations, media operations, including the possibility of black radio (propaganda radio stations) and political action within existing Indonesian institutions and organizations.”

The expectation was that if Sukarno was removed, a power struggle between the PKI and the army would follow. The (now pro-US) Army leadership was confident about the outcome of this struggle: in a confidential meeting with the Dutch ambassador, Army Chief of Staff Gen. Ahmad Yani (one of the generals killed on September 30) said the army was “reliable” and already making preparations for confrontation should the ailing president die.

But as long as Sukarno was protecting the PKI, crushing the communists was impossible. British Assistant Secretary of State Edward Peck suggested “there might be much to be said for encouraging a premature PKI coup during Sukarno’s lifetime.” The failed coup gave Peck what he wanted.

The killing of the generals was a boon for the army’s propaganda campaign against the PKI and, indirectly, against Sukarno. Sukarno’s refusal to condemn or ban the PKI, as the Right demanded following the failed coup, was exploited by the army to discredit him. In the following months, Sukarno was forced to hand more and more power to the army.

The theory that the violence was a sudden eruption of popular anger is belied by its gradual escalation. After the failed coup, the army supported anti-PKI demonstrations with transport and protection, and roughly a week after the death of the generals, mobs ransacked PKI offices as security forces looked on. Houses of PKI members followed.

The killings of (suspected) PKI members and supporters didn’t start until weeks after the September 30 coup attempt: massacres took place in Central Java in late October, then East Java in November, followed by Bali in December. In each instance the arrival of the Special Forces, commanded by Major Gen. Sarwo Edhie, preceded the killings.

Many victims were first arrested by militia groups supported by Edhie’s Special Forces. Prisoners were put into makeshift prison camps in remote locations and were often slain in groups, often by getting shot, stabbed, or having their skulls crushed with rocks and clubs. Much of the killing was done by young militia members of groups like Ansor, the youth wing of Nahdlatul Ulama, the country’s largest Muslim organization.

Ernst Utrecht, a left-wing supporter of Sukarno and former parliamentarian, estimates up to fifty thousand Indonesians participated in the massacre. After decades of propaganda and cover up, the number of victims cannot be precisely determined. Most historians assume the number of dead to be somewhere between five hundred thousand and 1 million, though Edhie himself claimed the number was 3 million.

Western powers supported the army in its campaign against the PKI. On October 17, the CIA worried the army might not go “all the way,” settling instead “for action against those directly involved in the murder of the generals and permit[ting] Sukarno to get much of his power back.”

To prevent this the CIA gave lists with the names of five thousand PKI members to the generals and organized the delivery of small arms and money to the army. The US embassy provided its own lists with two thousand names. In a meeting with British officials, Gen. Sukendro requested help for the army to “consolidate its position.” The meeting minutes reported on the “Army’s strategy” against the PKI and how “considerations [were] being made to meet the clamor of the nationalists and the religious elements for arms.”

Other Western powers also aided the massacre: the West German foreign secret service delivered arms and communication equipment worth DM300,000, while Indonesian refugee Osman Jusuf Helmi reported that Sweden had signed a contract with Suharto and Nasution “for an emergency purchase of $10,000,000 worth of small arms and ammunition” in December 1965.

Dutch ambassador Schiff reported on October 8 that the army was conducting an “intensive smear campaign” against the PKI, and concluded that the situation was “the best — and maybe last — chance of the army to assert itself politically.”

By the end of October, the US embassy received reports of violence against masses of PKI supporters in East, Central, and West Java. The US ambassador noted that the army was “moving relentlessly to exterminate the PKI.” A month later Schiff reported that “whole kampongs [villages]” had been slaughtered, supposedly as a result of local feuding.

The bloodshed achieved its aim of destroying the Indonesian left. In April 1966, Schiff’s minister of foreign affairs, future NATO Secretary Gen. Joseph Luns, noted “the blow dealt to the Communists (from which they are not likely to recover in the foreseeable future).” In July 1966, Australian Prime Minister Harold Holt remarked in a speech in New York that “with 50,000 to 1,000,000 Communist sympathizers knocked off, I think it is safe to assume a reorientation has taken place.”

A few weeks earlier the US State Department had rejoiced that, due to the killing of “up to 300,000 Communists” and another 1.6 million Indonesian Communists renouncing their membership, the number of communists in non-bloc countries had dropped by 42 percent in one year.

The aid Western officials gave the army in late 1965 and early 1966 was a crucial political signal to Indonesia’s new de facto rulers that the US and its allies were willing to support them. This backing was vital for the nascent regime because the Indonesian economy was in crisis, and Western capital remained hesitant to invest in Indonesia after Sukarno’s takeover of British and Dutch companies and calls to expropriate Western capital.

The military exploited the economic crisis to undermine what was left of Sukarno’s authority — British and US companies like Caltex, Goodyear, and US Rubber cut a deal with the army to channel corporate revenues into unnamed bank accounts, robbing the Indonesian state of an important source of foreign currency, further crippling Sukarno.

At the same time, the army was quick to placate its Western supporters. In December, Suharto reassured Western oil companies that the army “would not stand for precipitous moves” against them, and just days after Sukarno officially handed power to Suharto on March 11, 1966, the US mining company Freeport was allowed back into the country to extract the rich mineral resources in Irian Jaya.

A new foreign investment law that granted extremely favorable conditions for outside capital was drafted in close cooperation with the IMF, and starting in 1967 the new regime received $450 million annually from the Inter-Governmental Group on Indonesia (IGGI).

The IGGI included the Asian Development Bank, the IMF, the UN Development Program, the World Bank, Australia, Belgium, Britain, Canada, France, Germany, Italy, Japan, New Zealand, Switzerland, and the United States, and was chaired by the Netherlands. The Dutch chairmanship was suggested by US officials who hoped to divert attention from US (and Japanese) involvement in the deal.

Indonesia’s large cities were prioritized as aid recipients to stabilize the political situation. By 1968 the Suharto dictatorship was comfortably established and committed to pro-Western economic policies.

The Indonesian government still refuses to admit the killings were systematic violations of human rights. No one has ever been held accountable for the hundreds of thousands of deaths, and not a single one of the many known mass graves has been fully excavated to give the victims a decent burial. And in April it was announced that Sarwo Edhie would be declared a “national hero” for his deeds.

Above all, the massacres achieved their goal. To this day, the Indonesian left has not recovered.