Australian pilots have flown their first mission into war-torn Syria but did not drop any bombs.
The Australian Air Task Group, or ATG, completed its first mission in Syria overnight, returning to base without incident - and without firing any weapons. 
Two RAAF Hornets, an air-to-air refuelling aircraft and an E-7A Airborne Early Warning and Control aircraft combined during the mission.
The mission provided "on-call interdiction and dynamic targeting support", the department said in a statement on Saturday.
ATG Commander Stu Bellingham said the Hornets searched points of interest for enemy activity in eastern Syria, reporting to the international coalition's Combined Air Operations Centre through the E-7A aircraft.
"Daesh controls a large amount of territory in eastern Syria that serves as a source of recruitment and oil revenues, and as a base from which it continues to launch attacks into Iraq", Air Commodore Bellingham said.
"The Hornets were also prepared for any short notice high priority tasking which could include surveillance and weapons release."
The first mission came just four days after the Abbott government approved an extension of air strikes against Islamic State extremists from Iraq and into Syria.
Prime Minister Tony Abbott earlier alluded to the start of operations when he addressed the Nationals federal conference in Canberra.
He said Australia was responding with "strength" to the IS threat.
"And that's why our planes are now striking at terrorist target inside Syria as well as in Iraq," he said. He did not elaborate.
The ATG is part of Operation OKRA, the Australian Defence Force's contribution to the international effort to combat IS.
Defence says the ATG will continue to plan and conduct air strikes against Daesh strongholds in Iraq and Syria.