Since 2000 , the ADF 's expanded force structure and deployment capabilities have been put to the test on several occasions . Following the 11 September 2001 terrorist attacks on the United States , Australia committed a special forces task group and an air-to-air refuelling aircraft to operations in Afghanistan , and naval warships to the Persian Gulf as Operation Slipper . In 2003 , approximately 2,000 ADF personnel , including a special forces task group , three warships and 14 F/A -18 Hornet aircraft , took part in the invasion of Iraq
11 September 2001 terrorist attacks
September 11 attacks
Australian Defence Force