Defence Minister Christopher Pyne has visited troops in Iraq and declared Australia will there "until the job we set out to do is done".

Mr Pyne reassured Middle Eastern leaders Australia has no intention of withdrawing from the war-torn nation, where 600 troops have been based since 2014.

He has also suggested Australian troops could take a stronger role in the Middle East if the United States makes a speedy retreat.

His pledge comes after US President Donald Trump announced American troops would withdraw from Syria and wind back operations in Afghanistan, claiming Islamic State had been defeated.

President Trump has said he has no plans to withdraw US forces from Iraq but troop reductions in Syria and Afghanistan could have significant flow-on consequences.

"If the Americans left within six months from Syria, the impact on Australians presence in Iraq would be significant," Mr Pyne told The Sunday Telegraph while visiting Iraq.

"Would we be and feel secure without the Americans being in Syria? If the answer to that questions was yes, then it would probably mean we would strengthen our position in Iraq and see out this job."

Mr Pyne called on the US to clarify its Middle East policy following meetings with regional leaders.

"There's certainly concern among people I have spoken to that there is a lack of clarity around what the announcement by President Trump means," he said.

"I think all US allies and members of the coalition in Afghanistan and Iraq would like clarity of what the United States policy means for us and for them."

Middle Eastern leaders fear a swift US exit from Syria could spark a resurgence of the Islamic State.

At its peak, the terrorist group occupied a third of Iraq's territory, particularly on the border with Syria.