On the night of 30 September to 1 October 1965, detachments under the command of a group of officers of the Indonesian National Armed Forces set out to kidnap seven generals of the same armed forces. Three of the generals were killed at their homes during the kidnapping attempt, three were executed only hours later, and one was able to escape. If we set aside the official New Order (i.e. Suharto government) theory that this was a coup attempted by the PKI (Partai Komunis Indonesia), the remaining theories diverge between the PKI indeed being behind it, the assassination being the culmination of an internal army affair, and the operation being plotted with the knowledge and involvement of both the US government and General Suharto, who would emerge from it as Indonesia's new president.
Regardless of which of these theories is closest to the truth, it is safe to say that the assassination was just what the US government had been waiting for. With the PKI gaining more power within the government of Sukarno (president of Indonesia 1945-1967), and the president increasingly relying on the party's support, the US was worried that Indonesia would become a communist nation, which, according to the Cold War domino theory, would in turn strengthen communism in neighbouring countries. Thus, when the fervently anti-communist Indonesian military proceeded to physically destroy not only actual members of the PKI, but anyone even loosely or allegedly associated with the PKI, the US government not only looked upon it favourably, but encouraged the Indonesian military and provided it with money and communications equipment. Moreover, State Department and CIA officials drew up lists of names of alleged PKI operatives and handed them to the Indonesian military with the approval of US Ambassador to Indonesia Marshall Green.
People did not die at the hands of troops only. The military instigated the populace to participate in the mass killings, and thus death squads were formed that targeted anyone whose rape or murder could be, however loosely, ascribed to the cause of purging the communist menace. The US government's official position of course was that this was an outbreak of violence of Indonesians against Indonesians, and press coverage in Western Bloc countries generally framed the killings as a victory against communism.
Argentina was able to address its 1974-1983 killings and forced disappearances through a truth commission, which led to the 1985 Trial of the Juntas in which at least some of those indicted could be sentenced. The same can not be said for Indonesia, where the government's legislation for a truth commission has been nothing but a token exercise, and civil society organizations that are actually addressing 1965 face a grim outlook of the last survivors dying without as much as public acknowledgement of the crimes committed against them and their families, along with the last perpetrators dying in impunity. The problem thus becomes one of memory.