The United States has formally asked Australia to extend its air combat operations to hit Islamic State targets in Syria, but the government won't be rushing to make a decision.
Prime Minister Tony Abbott said it was a serious request and a response would be made in the next couple of weeks.
He warned consolidation of a terrorist state in Eastern Syria and northern Iraq would be a catastrophe for the world.
"It would be a disaster for Australia because what we have been seeing on an almost daily basis is the continued lure that this terrorist group, that this incipient terrorist state, is providing to misguided and impressionable young Australians," he told reporters in Perth on Friday.
Mr Abbott said as a courtesy he had advised Opposition Leader Bill Shorten of the request from the Pentagon. Labor will be formally briefed next week.
Australia dispatched an air task group to the Middle East in 2014, with the first combat mission flown on October 6.
The group now comprises six F/A-18 Hornets, an E-7A Wedgetail airborne early warning and control aircraft and a KC-30A airborne refueller, which fly from a pair of bases in the United Arab Emirates.
Australian aircraft operate up to the Iraq-Syria border but don't intrude into Syrian airspace, although Wedgetail and KC-30A aircraft support other coalition aircraft which do fly into Syria.
Mr Abbott said Daesh (Islamic State) was a movement of "almost incalculable unfathomable evil" and it was important that Australia play a part in disrupting, degrading and ultimately destroying this "death cult".
There was a little difference in the legalities of airstrikes on either side of the border but there was no difference in the morality, he said.
"This is an evil movement whether it is operating in Iraq or Syria," Mr Abbott said.
"In the end, when they don't respect the border, the question is why should we."
Aircraft from the US, Bahrain, Canada, Saudi Arabia and UAE have hit targets in Syria. Britain is considering joining in.
However, coalition aircraft routinely conduct many more strikes on Iraq than Syria, principally because of the difficulties in reliably targeting the militants without inflicting civilian casualties.
Opposition Leader Bill Shorten said Labor always sought to achieve bipartisanship on national security.
"We believe there is no more important role for the parliament than to make sure that Australians are safe," he told reporters in Perth.
Australian Strategic Policy Institute director Peter Jennings said the small extension of the campaign made sense militarily.
"There is very little point if we can only confine our strikes to one side of what is now an invisible and non-existent border between Syria and Iraq," he told Sky News.
Mr Jennings said air power alone would never defeat IS, but it would be useful to be able to target IS leaders, now in something of a sanctuary inside Syria.
"If nothing else they are going to need to change their rules of engagement to make it possible to target the IS leadership," he said.
"That unfortunately may be at the expense of allowing some civilian casualties."
