Imagine you live in New York or Chicago, and one day you look out the window and see this.

And Canadians go, hehehe, we did it! Hehehe. And the US government goes, we must not shoot back because, you know, the EU is gonna object and stuff. So, we'll just sit here, let them bomb Chicago as much as they like, and meanwhile, we will think how we can become a better nation, so they won't want to bomb us again. Win-win!