LH -

Is the US the only military threat to Canada? Almost certainly. Who else is going to make it? Even if they were capable of the kind of assault performed without ANY land base of operations (unlikely; even the US desperately wanted a land base to attack a little, relatively defenseless country like Iraq), said attacker would also have to contend with your next door neighbor and ally being capable of getting a large army there virtually overnight.

Logistically speaking, yes, the US is really Canada's only potential threat. While being your only threat, we are also your best protection.

Is the US a threat to Canada? I very seriously doubt it, at least in the military sense. Most Americans consider Canada practically part of the US, and while it's easy to mount a publicity campaign against somewhere very distant with, you know, foreigners! There would have to be literally decades of a constant propaganda campaign about the "danger from the north," sustained over multiple government administrations. Nor would the other western allies stand for it, if not for altruistic reasons, simply because if the US would attack Canada, it would be obvious they'd attack any of the others, too.

Even if the US were seized by a warlike dictator and the Constitution suspended, Canada would be WAY down the list of targets when there are so many others the US could attack and sieze control of with relative impunity from it's western allies and from the wrath of it's citizens.

But maybe the US is a threat in the economic sense. An economic and political "annexation" of Canada is possible and probably desirable to some. Economic control over the resources of Canada would be MUCH cheaper and better for business and political gain than a war where we might suffer our own civilian casualties -- something almost everywhere else understands but is totally unthinkable to the US.