No, but if the artists formerly known as the U.S. Customs Service (now the "Bureau of Customs and Border Protection") are directed to from on high (ahem!), they can do something approximately equivalent to the "work to rule" technique that longshoremen have been known to employ in labor disputes, and inspect every last carton in every last freight container--a right Customs has always reserved itself, but which it has been impractical to exercise in the age of universal freight containerization. The USA is Canada's principal trading partner, and as such is in a position to give the northern neighbor's economic privates a not-so friendly squeeze should the latter be foolish enough to believe all that guff about their sovereignty being respected.
Of course, that could also cause pain south of the long border, and if Canada stuck to its guns I'd guess that the folks who bankroll our regime, for whom this isn't really a burning issue (it may be red meat for the sector of the electorate that watches "Fox News," but that's another matter), would pass word to knock it off after a few weeks.
It could be interesting. I'll keep a watch on this story.
cordially,