In the wake of the strike on Friday, Prime Minister Malcolm Turnbull said that the US had not requested expanded military help from Australia. The missile attack on Shayrat air base - which, along with other US allies, Australia has strongly endorsed - was a "single strike" to deter further use of chemical weapons rather than the start of any deepened military effort in Syria.

Senior sources indicated to Fairfax Media that they did not see regime change as part of the US government's plans.

Mr Turnbull, however, said that Russia had a "solemn obligation" to stop its "client" from using such weapons prohibited under international law.

"The whole world is crying out for a settlement in Syria," he said. "When the United States has shown its full force in response to this shocking chemical attack, surely now is the time when the nations of the world and the great powers engaged in the Syrian conflict zone can come together and bring this war to an end."

Labor leader Bill Shorten also backed the strike, saying that the "illegal and abhorrent use of chemical weapons . . . demanded a strong response". Opposition foreign affairs spokeswoman Penny Wong joined calls for Russia and Iran - Syria's other major ally - to rein in the regime.

Defence Minister Marise Payne said that the Australian Defence Force had "taken appropriate measures in light of this operation" to make sure its aircraft could not be threatened by any retaliation by the Syrian regime or its allies.

Senior government sources played down the prospect the missile strike would lead to further military entanglement, noting that Australia's legal mandate for carrying out air strikes against the so-called Islamic State in north-eastern Syria was based on the collective self-defence of Iraq.

This would not extend to attacking Assad regime forces in Syria and a new legal justification would have to be found, sources said.

Defence experts similarly said that the strike did not presage any attempt to pursue a new strategy of dislodging Mr Assad. Indeed, if any major shift were to occur, some experts said, it would be Russia abandoning its support for Mr Assad in favour of an alternative.

One senior Canberra source said that Russia would easily ditch Mr Assad if it decided he was more of a liability than an asset - a situation that the chemical attack might constitute, given the pressure it had created on Moscow.

Lowy Institute Middle East expert Rodger Shanahan said that "Russia would have been as angry as the Americans about the Syrians doing a chemical weapons attack".

"You have your ally who you've gone out on a limb for ??? and they do something that was stupid at all levels, as well as immoral."

He noted that Iran, which is Assad's other most powerful ally, has a visceral hatred of chemical weapons, given Saddam Hussein used them against its forces in the war between the two countries in the 1980s.

Bob Bowker, a former ambassador to Egypt now with the Australian National University, said neither Russia nor Iran wanted to damage relations with the US over Syria.

"I don't see either the Russians or the Iranians deciding that they have any interest in escalation of the conflict," he said.

And Mr Assad would probably not retaliate without the backing of his major allies, he said.

Peter Jennings of the Australian Strategic Policy Institute said that Mr Assad may be more nervous about using Syria's air force in the wake of the attack. He also said Mr Trump had also sent a powerful signal during the visit of Chinese President Xi Jinping, who may be wondering "what does this mean for North Korea?"

"This guy is much more willing to use military force and that will lead to more Chinese uncertainty about how to deal with President Trump."

Follow us on Facebook