- Indonesia has until recently been a colony
- Its leader, President Sukarno, is bitterly anti-colonial, and a nationalist
- He believes that Malaya is controlled by the British
- Indonesia has a strong communist party - Sukarno needs to keep them happy
- Indonesia has a strong army - Sukarno needs to keep them happy
- Indonesia has recently taken Dutch New Guinea by threat and bluff - it now shares a border with Papua-New Guinea, which is controlled by Australia.