For the first time, Indonesia has joined international air war games in Australia.
Fighter jets from Australia, Singapore, Indonesia, Thailand and the United States are taking part in a combined defence forces exercise called Pitch Black.
The two-week mock combat operation is held in Darwin every two years because of its open-air space.
David Thiele of the Royal Australian Air Force says it is significant that Indonesia has decided to join in. "It shows a strong growth in the agreements between Australia and Indonesia, as well as our military co-operation," he says.
It will also be the first time the RAAF has come in contact with Indonesia's Russian-made Sukhoi SU-30 fighter aircraft.
The planes have been built to compete with American-made FA-18s, which are used by the Australian and American air forces.
It is the first time Indonesia has sent its primary air defence aircraft to a foreign nation.
The move comes after talks earlier this month in Darwin between Indonesia's President Susilo Bambang Yudhoyono and Australian prime minister Julia Gillard.