Apart from the risk of a domestic backlash, New Zealand has also been winding up a big and expensive campaign to win a seat on the United Nations Security Council, with the boast of an "independent foreign policy" at its heart. If Key is inclined to commit personnel to the dangerous, amorphous and protracted military operation being led by the US, he'd be mad to do it before the vote in New York on Wednesday.
But the Prime Minister has performed a soft-shoe shuffle on the subject over the past four months.
When he visited New York and Washington in June to promote the Security Council bid, the US had started building a coalition for action against Isis. Key said there was no foreseeable prospect of NZ special forces being involved. But could he rule out an SAS deployment to Iraq? His reply: "I would say yes."
Key later remarked that before offering its support, New Zealand would "look to the Security Council for its view and its sanction".
In Washington, John Kerry made it clear that New Zealand was taken for granted. "We don't have to ask, this is one where we know that New Zealand stands with us."
A fortnight ago, without any UN mandate, New Zealand was named by the US as one of 62 countries joining an "international effort to counter Isil", albeit so far only in providing humanitarian aid.
This week, Key conceded special forces might after all be sent to join the war effort, including in a possible reconnaissance role in Iraq.
An SAS squad of 12 had been put into "pre-deployment mode", according to 3 News.
This would be done reluctantly, says Key. He has acknowledged that "history tells you that going into places like Iraq [is] fraught with difficulty and danger", that air campaigns "only get you so far", and as our experience in Afghanistan shows, "once you commit you're there for a very, very long period of time".
Any New Zealand contribution will inevitably be small and chiefly symbolic. There is no cause to rush in the way Australia has - an act of "utmost foolishness", in the words of former prime minister Malcolm Fraser. Parliament and the public should be given time to consider all the practical and moral arguments.
No one credibly suggests air attacks will magic away Isis. This is a war without any obvious end-point, a war which, history advises, will claim untold civilian lives and suffer mission creep.
Will sending troops increase New Zealand vulnerability to a domestic terror attack, perhaps from the growing numbers of extremists who we're told want to join the Isis cause?
Key says the risk is negligible, and that in any case that shouldn't deter us from joining the campaign. That argument warrants greater scrutiny.
Is the case for war sound? The bloodthirsty, barbaric tactics and propaganda of Isis are sickening. But at the same time we continue cordial relations with a nation such as Saudi Arabia, from which much of the funding of Isis is said to originate, and where, as opponents of this new war point out, 59 people have been beheaded this year for offences including adultery, sorcery and witchcraft.
Would not New Zealand military, medical and humanitarian efforts be better deployed, say, as part of the global fight against Ebola? If it is the scale of brutality that motivates us, shouldn't we be putting everything into UN efforts to stabilise the Democratic Republic of Congo, where war has killed five million people since 1998?
The Prime Minister has said he'll consult other parties on any action taken, and that Parliament will be given a chance to debate on any commitment to the US-led operation.
That is insufficient. We should follow the lead of Britain, where MPs' sanction is now considered essential before going to war. A parliamentary vote is the bare minimum.
On first-name terms, twice
No point pretending we're not all thinking the same thing. The emergence of Colin Craig. The swelling power base for Russel Norman. And the remarkable rise to party leader and parliamentary underwotsit by David Seymour. Suddenly these people with two first names are everywhere. It's enough to make you wonder even whether the "s" at the end of Winston Peters is for real.
Let me be completely clear: I have nothing personally against people with two first names. Some of my best friends have two first names, not that they make a big deal out of it. I admire musician Samuel Scott. I'm a huge Cory Jane fan. All I'm saying is, you know, one talks to people and it's clear not everyone is comfortable with their type in positions of power.
Put it this way. I don't think New Zealand is ready for a Prime Minister with two first names.
It would help if they didn't insist on flaunting it, saying their names aloud here, signing their names in ink there. And if you doubt whether these people - and I personally like them, don't get me wrong! - are rising sneakily everywhere, just ask yourself this: which Government MP leaped all of a sudden from the backbenches straight into the Cabinet this week? It was Maggie Barry.
