My guess: to weaken Canada's economy, limit Canada's international standing, bankrupt the sovereign state, cause rise of populism and voters thereof, have its people overthrow the government, then absorb the former country as a state to extract its natural resources, to fulfill manifest destiny.
Other than the current tariff narrative, it's fairly standard CIA play when we look at what they did to Latin America already.
I am addressing directly why the Republicans want this, not why the current president wants this. Even if the current president changes, the Republicans will still pursue the annexation of Canada with financial interest.
Donald wants to bully anyone he can into submission; the requirements are designed to be obscene so that agreeing to them is akin to kissing the ring.
That and trying to get more willing sycophants installed in power whenever possible (a little gem hidden in the latest batch of requirements: Canada should stop protecting the French language status. If you know anything about Canada, you know that agreeing to this would be a political suicide for the party in power).
This is a thought terminating cliche. This is just the latest move in a long term strategic effort to undermine Canada's sovereignty. Zoom out, and that in it of itself is part of an even broader strategic effort to reorganize alliances which built the world order.
Everywhere there are criticisms of Trump, his administration, and their goals, there is always this commentary which not only fails to serve as an accurate representation of present situations, but more importantly, it serves to distract from the chronology of events which led us here, blinding the broader conversation from creating inferences of what will happen next which stifles the conversation from its most natural next reply: What are they actually doing, and what do we do if it does not benefit us?
I believe in sovereign states well enough to have 100% respect for Canada-first policies as well as America-first in the US.
Things worked so well for so many decades with much lesser rebalancing, that the only explanation would be some serious defect arising that was not there until recent years or days.
This is just Trump's way of telling Americans, if they can't afford to pay way more going forward for everything into the foreseeable future, toilet paper is the least of their worries.
He doesn't have to detail it out loud, but there are plenty of good old American corncobs which have fallen into disuse for this purpose, and it wouldn't be nearly as unpleasant as it was in the outhouse days.
Except for those who may not be able to afford a rising water bill at some point :(
In the end it confirms his idea of "winning" amounts to shit on a stick.
Same energy as a 13-year-old boy bullying his little brother just because of his own hormone-driven insecurity.