Wonder if the PM knows that before we intercept an incoming ballistic missile, we know where it's gonna land. It's ballistic - it travels on a predetermined course.
So the question is, do we give them the option of buying a "shootdown" for, say, $20B (US) when the time comes ("you have 15 seconds to decide, $20B (US) and we'll attempt an intercept; or not, your choice - 10 seconds left"), or just let it land on Canadian soil.
"Hi, this is Don at the Pentagon. How may I help you? You want what? You have an incoming missle and you want us to shoot it down? Oh. Ok. May I have your credit card number, please?"