The US actively supported the Indonesian military’s killing of as many as 1m suspected Communist sympathisers in the mid-1960s despite concerns about the reasons behind the massacre, according to newly declassified American documents.

Some 30,000 pages of files from the US embassy in Jakarta — declassified on Tuesday — showed that the US provided the Indonesian military with money, weapons and lists of Communist officials during the 1965-66 killings, which came at the height of anti-Communist sentiment in the Cold War. 

The documents also show that the US had credible information to contradict the Indonesian military’s claims that the killing of six army generals in a botched September 1965 coup had been ordered by the Indonesian Communist party (PKI).