It didn't sound like a particularly well thought-out plan to me.
Can the US military handle Canadian winters? Invading Winnipeg would be a really, really baaaad idea if you don't like the cold, seriously! It gets colder than Alaska there. And if your tanks and armored personnel carriers run on diesel, they better have their own nuclear powered block heaters too. Of course I suppose you might invade in the summer. That'd be smarter.
It's not like you'd encounter any resistance. But if you invade and still block our beef and softwood lumber exports, we'll kick your asses!