Today is the 50th anniversary of the formation of the "30 September Movement" and the beginning of a chain of events in Indonesia which led to the to death of over 500,000 people.
This guest editorial in yesterday's New York Times characterizes the events as: "a mass slaughter", "murder", and "genocide"... it also compares the actions to that of the Nazis (presumably meant to imply "genocide", again). Elsewhere the events have also been characterized as a "purge" or a "civil war", the last term no doubt indicating the least moral outrage.
Which of these or other terms are applicable?
They are a mass slaugther by Indonesian to another Indonesian. They are done by the anti communist faction of the army and other people/communities who are against the PKI. There are also people who take advantage this to settle their personal conflict too.
There is a coup by a certain wing of the army & some faction of the PKI, but the coup easily being stopped by Soeharto. So there is no civil war here as they swiftly defeat the conspirator of the coup.