I'll pick up on a couple of things there.
The math that you're illustrating, I think captures the fact that this is not a destabilizing system. There are less than 50 interceptors at present that physically have to hit an incoming missile. The Russians have thousands of ballistic missiles of their own, and the Chinese have multiple hundreds. Just based on the sheer math and the way they're going to be employed, right now I don't see how this could be more widely destabilizing.
I think the use of that system, even against a rogue state, to deal with the different decoy issues is one where you.... You don't have a lot of ability to defend yourself against many different types of attacks, just because of the limitations and the strict math. If there were an opportunity for Canada to participate in terms of research and development, I think that would be an added bonus, but I think the main reason to do this is to provide for the security of Canadians.
To touch on something that was raised earlier about the issue of the threat and whether or not this is a direct threat to Canada, the traditional definition is that a threat is a mix of capability and intent. The North Koreans have the capability. Maybe right now we don't think they have the intent to actually directly target Canada, but again, I would say that it's more than 8,000 kilometres across the Pacific, and Victoria—I checked just before coming—is about 130 kilometres from Seattle as the crow flies, while I think that for Vancouver it's under 250 kilometres.
I don't think it's unreasonable to think that even if you're aiming for Seattle, where there are major industrial-based considerations with the Boeing plant in the region and with major United States military installations in that region.... If Seattle is viewed as a strategic target by some rogue state, I don't think it's at all implausible to think that one of those missiles may end up on the Canadian side of the border even if the intent were to go further south. We don't know what could happen in terms of the North Koreans' intent in the future, and that may change, but if you don't have a capability or any ability on your own to have any possibility of defending yourself against that, then you're left to the fortunes of others.