Tomorrow, Mr Key will outline the contributions to the campaign the Government believes would make sense.
The types of contribution expected to be canvassed are humanitarian aid to add to the $1 million already given, beefed-up diplomatic representation, and non-combat military help including airlift capability and intelligence assistance.
He is not likely to support direct combat but may set out narrow circumstances in which it would be considered, and where.
"You'll have a pretty clear pathway of the road we intend to travel," he said yesterday at his post-Cabinet press conference.
Watch: Isis fight - NZ won't be a target
And in a major departure from tradition, he will also set out the best estimates by intelligence agencies of New Zealand residents who are already fighting with Isis, are financially supporting the group or are wanting to fight.
He will explain how he wants the law changed to make it easier to prevent people leaving New Zealand to fight with the terrorist organisation - so-called foreign fighters - and what criminal charges they should face on their return.
He said he was hopeful of getting wide support across Parliament and while there would be a select committee process, he wanted the law passed as quickly as possible.
Asked about reports that Isis massacred more than 322 members of a tribe in Anbar province and dumped the bodies of women and children in a well, Mr Key said it was a "dangerous and brutal and ugly" group of terrorists.
"My own view is that these people present one of the more significant threats in modern times primarily because they are very well organised and they are very well resourced."
He said the delay in making any announcement was down to careful decision-making.
It had nothing to do with meeting other leaders, such as President Barack Obama, at Apec next week or at the G20 the week after.
Who is contributing what to the US-led coalition against Islamic State
• Targeted air strikes; special forces or other troops; military personnel to train or advise Iraqi troops or Kurdish fighters; military equipment for Iraqis or Kurds; humanitarian aid: United States, Britain, Australia, Canada.
• Air strikes; military equipment; aid: Denmark, the Netherlands.
• Air strikes; aid: France, Belgium, Saudi Arabia, United Arab Emirates.
• Air strikes: Jordan, Bahrain.
• Military personnel for training; military equipment; aid: Germany, Italy.
• Military personnel for training; aid: Norway.
• Military equipment; air transport; aid: Estonia.
• Military equipment; aid: Czech Republic, Albania, Hungary.
• Military equipment: Bulgaria, Croatia.
• Air transport: Qatar.
• Humanitarian aid: Turkey, Sweden, Kuwait, Switzerland, Japan, Austria, New Zealand, South Korea, Iceland, Ireland, Latvia, Spain, Slovakia, Norway, Luxembourg, European Union.
• Unspecified, but cited by State Department in Washington as part of coalition: Andorra, Bosnia, Lithuania, Macedonia, Malta, Mexico, Moldova, Morocco, Portugal, Serbia, Slovenia, Tunisia, Ukraine.
• Providing bases or staging posts for air strikes, drones, air transport or foreign troops, or use of territory to launch operations against Islamic State: Iraq, Turkey, Qatar, Albania, Cyprus, Greece, Kuwait.
- compiled by John Armstrong
