Nearly five decades after the 1965 abortive coup, which was blamed on the Indonesian Communist Party (PKI), historians, observers and direct witnesses are still unable to agree about the masterminds behind the historical events.

Speaking at the launch of Jusuf Wanandi’s memoirs Shades of Grey in Jakarta on Thursday, panelists recounted the confusing state of events during those fateful days.

Jusuf maintains that then president Sukarno could not have been solely responsible for the actions of the PKI due to his ailing health and the rapidity of events....