The Federal Government is sending 600 Australian troops to the Middle East in preparation for military action against Islamic State (IS) militants in Iraq.
Prime Minister Tony Abbott said the United States had specifically requested Australia contribute to an international strike against the militants, who have captured large swathes of territory in Iraq and Syria.
Mr Abbott said around 200 troops would be sent to the United Arab Emirates shortly, including a Special Forces contingent "that could act as military advisers to the Iraqi armed forces or to the Peshmerga".
They would be followed by around 400 Air Force personnel, up to eight super hornets, an early warning and control aircraft and an aerial refuelling aircraft.
Mr Abbott said "there are obviously further decisions to be taken" before Australian forces commit to combat action against IS militants.
"Should this extend into combat operations, it could go on for some time," he said.
Dr Rodger Shanahan, a former Army officer who is now a non-resident fellow with the Lowy Institute, said it was hard to say how long the mission will last.
"We don't know what the mission itself is, because it's a precautionary deployment, but you would assume you wouldn't deploy unless they assume they're going to be used," he told ABC News 24.
"We assume it's going to be battling Islamic State. The question is how long is a piece of string? You assume this will last months at a minimum."