Imagine you’re a country being attacked by a well-equipped foreign army — infantry, tanks, amphibious assault units, artillery, paratroopers, air assault, the works. You have no armed forces to speak of — except a big honking nuclear warhead that you can detonate over the enemy capital. You have no other way of defending yourself: it’s surrender or go nuclear. What do you do?

That, in a nutshell, is what a minority Parliament is like: the ultimate in political asymmetric warfare. In the Westminster system, the governing party has almost every advantage. It controls the public purse and the legislative agenda. In the case of the Harper Conservatives, they also have a considerable financial advantage over their opponents. They can, if they choose to do so, run as roughshod over their opponents as the Constitution and parliamentary procedure will allow. But if they do not have a majority in the House, the Opposition retains the nuclear option: push us far enough, and we will defeat you.

By threatening to strip away political parties’ public financing, the Harper government launched a direct attack on the opposition parties, because they rely on that money to survive far more than the Conservatives do. Only the worst kind of abusive bully would have expected them to shut up and take it. Of course they were going to respond to something that threatened their existence. The problem is, defeating the government — the nuclear option — is the only weapon at their disposal. It’s a wildly disproportionate response, it’s overkill, but they have nothing else that will work. What else were they supposed to do? Relax, lie back and try to enjoy it?

The Harper government gambled that the opposition wouldn’t defeat them: it was too soon after an election and the Liberals were in the midst of a leadership contest. That a third option — defeat the government and form a coalition government — soon presented itself was not something, I think, for which they were prepared.

And with that genie out of the bottle, things slipped further out of Mr. Harper’s control (imagine that).

Now, no one can back down without considerable loss of face. For the Harper government to survive, there will almost certainly have to be a number of resignations — Guy Giorno, Harper’s chief of staff, and finance minister Jim Flaherty at least, possibly even Mr. Harper himself — along with a genuine display of contrition. But Mr. Harper does not appear to be in a conciliatory mood. It’s possible that as an outgoing leader, Mr. Dion could afford to lose face more, but the collapse or defeat of the coalition would be Pyrrhic. Once the new Liberal leader was in place and enough of an interval had passed to allow for another election, the opposition would be out for blood.

In the meantime, let’s see what happens at Rideau Hall this morning.