OTTAWA - Foreign Affairs Minister Mélanie Joly says Canada has been considering a “game plan” for how it would respond if the United States takes a far-right, authoritarian shift after next year’s presidential elections.
Theres other considerations beyond state to state war with the US.
I'm not Canadian and don't actually have an opinion, but here's other reasons they might increase their defense budget because of US destabilization. Decreased global stability due to loss of neighboring super power. Non state actors like terrorists or refugees leaving the US.
I don't think that Canada will be fighting the New Confederacy or the New England Union of Democratic Socialists in 2028, but there are still reasons that a diminished US would mean Canada should spend new money on defense.
Military spending on what though? The CAF is woefully dependent on the US for basically everything. Hell they probably could turn off those F-35s by pressing a button.