The Prime Minister says he's not ruling out New Zealand involvement in a military intervention into Syria, even without a United Nations mandate.
John Key says he spoke with the UN Secretary General Ban Ki-Moon on Thursday morning, who left him in no doubt about the gravity of the situation.
He says New Zealand would still prefer the Security Council to negotiate a resolution but if that did not happen, this country would have to weigh up its options.
The Government received a general briefing from the United States through its UN diplomats in New York on Wednesday night.
Mr Key says there are no specific requests for action from New Zealand but it is more a general update on how the situation is developing.
He says New Zealand's response may well end up being moral support for a military response, rather than active participation.
"If it was UN-mandated, that's an easier question to answer I think. New Zealand's historical support has been clear there. If it wasn't UN-mandated then we would need to look at it on its merits at the time."
Action 'last resort' says Labour
The Labour Party says the Government must exhaust all possible options, before it considers unmandated action against Syria.
Labour foreign affairs spokesperson Phil Goff says unsanctioned action must only be taken as a last resort.
The Green Party says New Zealand should not be part of any unmandated action against Syria, under any circumstances.
Greens co-leader Metiria Turei says New Zealand should completely rule out any action that hasn't been sanctioned by the UN.
Earlier, Mr Goff said it was clear the United States was working to build support for action against Syria.
Mr Goff, who served as the Minister for Foreign Affairs from 1999 - 2005, told Morning Report the briefings would involve what evidence there was that the Assam regime was responsible for a chemical attack in Syria on 21 August.
He says the briefings would probably also include discussions about options for action through the Security Council. In the event of a veto by another power, these may involve a strategic strike against a military target.
He says he expects the United States will seek New Zealand's support for action but not military involvement.