Any request from the United States to join future action against the Syrian regime would be treated "pretty cautiously", Prime Minister Bill English says.

Cabinet is likely to today discuss the US air strike on Syria on Friday, as US ambassador to the United Nations, Nikki Haley, tells media that removing Syrian President Bashar al-Assad from power is a priority and "inevitable".

The air strikes have angered Syria's ally Russia, but English told Mike Hosking on ZB this morning he did not believe the worst-case scenarios floated by some were likely.

"We don't see any reason for some escalation into some of this hyper-commentary that has been going on about [the] third world war and so on. I don't see any reason why the US or Russia have a reason to escalate it in that way."

Advertisement

English said no request about future action in Syria had been received from the Trump Administration.

"We would be very cautious about any request, and there has been no request and no indication that there will be a request coming.

"In Syria, everyone understands it is a very complex situation [and] hard to see a path to success. Our preference, of course, is a political-type settlement where there isn't ongoing killings and atrocities."

Australian Prime Minister Malcolm Turnbull has been more direct, saying over the weekend that Assad's crimes were "so enormous and of course now so recent, it is difficult to see how a political solution can be crafted that has him with a continuing role."

New Zealand had supported the air strikes as a "proportional response to a specific incident - the chemical weapons atrocity", English said.

Yesterday Defence Minister Gerry Brownlee said, in his assessment, the air strikes were probably a one-off, and he was not expecting any US request for New Zealand to contribute anything more than it already is against Isis in Iraq.

"It would be fair to say we are keeping a close watch on it - the whole world is keeping a close watch on it.

"But it looks like it's much more along the lines of a one-off shot-over-the-bows of both the Syrian regime and their supporters to say this sort of behaviour is not acceptable."

New Zealand was notified in advance of the strike as a matter of courtesy because it was part of the US-led Coalition against Isis in Iraq.

New Zealand and Australia are running a training mission in Camp Taji for Iraqi forces fighting Isis in Iraq, with New Zealand contributing 106 Defence Force personnel to the effort.

Australia which, unlike New Zealand, is a formal ally of the United States, has also been involved in air strikes with the US against Isis in both Iraq and Syria and will advise and assist role near the front line.