Australian forces could be involved in the United States-led operation against Islamic State militants for many months, Prime Minister Tony Abbott says.
The United States specifically requested Australia contribute to an international strike against the militants who have captured large areas of territory in Iraq and Syria, Mr Abbott said.
About 600 Australian personnel, including special forces soldiers, will soon head to the Middle East, the ABC reports.
"I have to warn the Australian people that should this preparation and deployment extend into combat operations that this could go on for quite some time," he said.
"Months rather than weeks. Perhaps many, many months indeed."
About 200 personnel will be sent to the United Arab Emirates within days, including a Special Forces contingent "that could act as military advisers to the Iraqi or Kurdish forces".
They will be followed by air force personnel, fighter jets and other planes.
However, Mr Abbott said he had not made a final decision on whether Australian forces would join direct combat.
Independent MP Andrew Wilkie strongly opposed the 2003 Iraq War but said the circumstances appeared to be different this time around. He said most people understood that the situation in Iraq was dire.
But Mr Wilkie said Australia's participation in the international mission would make it more of a terrorist target.