John Key has arrived in the United States ahead of a round of crucial meetings - including a formal White House visit on Saturday.
His visit will begin on a sombre note, when he lays a wreath at the 9/11 memorial overnight (NZ time).
But the Washington leg of his trip could be overshadowed by the worsening Iraq crisis amid speculation the US is mulling the use of special forces soldiers, among other options, including air strikes.
Iraq is on the edge of civil war as an offensive by extremist militants sweeps through northern Iraq, with graphic images purporting to show bloody executions causing international condemnation.
The US has ruled out sending combat troops back to the country but is mulling other options including the use of special forces soldiers in an advisory capacity.
Britain has disclosed that its special forces will provide counter-terrorism expertise in Iraq.
Ahead of his departure from New Zealand Key would not rule out the possibility of contributing to humanitarian or military action but said the likelihood of New Zealand sending troops was low.
He also stressed that any request from the US was "unlikely".
But it would be surprising if Iraq did not come up in his meeting with US Secretary of State John Kerry on Friday morning ahead of Key's formal meeting with US President Barack Obama.
Key is also meeting US Defence Secretary Chuck Hagel at the Pentagon.
Recent revelations about Kiwis fighting in Syria have bought the violence in the Middle East closer to home.
New Zealand special forces served in Afghanistan in an advisory and training capacity, as well as in counter-terrorism activities, and the US made it clear it valued their contribution.
But it is not believed that New Zealand special forces served in Iraq during the war there, especially given that New Zealand opposed the invasion, though the policy at that time was not to disclose their activities..
Richard Allen, the former national security advisor to President Ronald Reagan, said that while it was "conceivable" the US might ask New Zealand to sign up to any action in Iraq, he did not believe it would go anywhere given public sentiment in New Zealand during the last Iraq offensive.
"There's a veritable snowballs chance . . . that New Zealand is going to be sending any troops to Iraq and I dont think it should," he said.
"I dont think there's any reason why it would."
Allan was highly critical of the Obama administration's Iraq policy, saying "the administration has simply abandoned Iraq and left in an irresponsible fashion".
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