For evidence that John Key is the ultimate political mercenary, look no further than the U-turn on Iraq.
Like a true mercenary, the Prime Minister has a paymaster -- public opinion.
John Key knows that mission creep is easy if the public is on your side.
A Newshub poll in November last year showed 65 percent of Kiwis want the troops to stay on in Camp Taji.
So while it is by far his biggest U-turn/flip-flop/about-face/turnaround, John Key is happy to suck up the criticism because while it is a big U-turn, it is also one of the best for him politically.
John Key saw an opportunity, and he took it. He has made an informed call that he will not be punished for it by voters. In fact, he is subtly goading the media to criticise him for it, knowing polls show the majority of the public don't care.
The rest of the political calculation makes it a no-brainer to stay on.
The troops are as safe as they can be in a war zone. Having visited Iraq, John Key has also seen how safe the troops are at Camp Taji. He knows there is a slim chance of any casualties, a slim chance of any body bags coming home in Election year.
He keeps the United States and other allies happy. Never underestimate the huge pressure New Zealand comes under.
He keeps the "good deal" of Camp Taji. The innate deal-maker in him knows if he pulled the troops out to keep his two-year promise and then, rather than "do nothing", sent another deployment of troops -- say for instance the SAS -- they may well be put in a lot more dangerous role/place.
He also protects himself from doing nothing against Islamic State. If the troops pulled out in May next year, he would have gone into the election campaign without helping the "war on terror".
He's instead decided he wants to leave Labour in that position, and create a point of difference on the security front. The reality is that terror attacks will likely continue and security could be a bigger issue than it has previously in a New Zealand election.
So the U-turn makes sense for John Key politically. After all, he created the political cul-de-sac with his own assurances.
The reality is John Key gave those assurances because nobody knew how the public would take the Iraq deployment. He gave the assurances to help stack up the case for what was a dangerous political decision.
Public opinion now shows it is not a risk to the Government's popularity anymore. And public opinion is the paymaster of John Key the political mercenary.