The Prime Minister has given his strongest indication yet that New Zealand will be offering support in the fight against Islamic State (IS) in the Middle East.
Mr Key said he expected to make a decision by the middle of next month.
He said there was a range of assistance that could be provided and sending troops was at the outer edge of what he might do.
Mr Key told TV3's The Nation it would be very odd if New Zealand did not join the many like-minded countries that are all involved in some form in fighting IS.
"It would be very odd for New Zealand to be in a situation where the UK, the United States and Australia and Canada and France and Germany and Belgium and lots of like-minded countries, the Netherlands, are all involved in some form, in fighting a very serious terrorist group, and for New Zealand to do absolutely nothing," he said.
"The question is what we do, I think, rather than whether we do something."
Mr Key said he would be speaking soon about New Zealanders who have aligned themselves with foreign fighters in the Middle East.
But he said he was yet to decide whether he would reveal the numbers involved, which he has said would surprise most New Zealanders.
Mr Key said he felt the public should know and he was working with his security advisors on how much he could reveal.
"If I'm allowed to, I will spell out within a range what those numbers look like," he said.
"There are different categories in that group of foreign fighters. So they are people who are either in the country overseas fighting, there are people who are looking to leave and there are people who are looking to be part of the overall engagement, so they might fund those activities."
He said the Government was still considering what, if anything, New Zealand could contribute to the fight against IS.
The BBC has reported that America's top general will convene an international meeting of military commanders in Washington next week to discuss the campaign against IS militants in Syria and Iraq.
The Pentagon has said General Martin Dempsey, the Chairman of the Joint Chiefs of Staff, will welcome more than 20 coalition partners to Andrews Air Force Base on Tuesday.