Prime Minister John Key is supporting Australia's decision to extend its bombing campaign against Islamic State (IS) from Iraq across the border into Syria.
The move puts Canberra at odds with the United Nations Security Council, which does not endorse the West's military action.
Mr Key's comments came on the sidelines of the Pacific Island Forum in Papua New Guinea, moving him into legally tricky territory.
In a couple of hours Australian Prime Minister Tony Abbott will arrive in Port Moresby, fresh from announcing the plans.
Mr Key is sizing up New Zealand's position, not ruling out lending moral support to Australia and backing its decision to drop more bombs.
Air strikes in Syria will not get the legal go-ahead from the United Nations Security Council. Russia has the power to veto any moves, and always would.
But because New Zealand is currently sitting on the council, by supporting air strikes Mr Key would be undermining its purpose.
Australia is following the United States' lead. It's already bombing in Syria, arguing air strikes are allowed by international law under what's called "collective self-defence".
It's a work-around when you can't get a Security Council mandate.
"I'm not going to criticise other countries for coming up with legal workarounds when the Security Council fails to act," says Foreign Affairs Minister Murray McCully.
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