Telling a sovereign nation, and the US’s closest ally, it should become the 51st US state isn’t making war, but it’s way more than imposing tariffs in contravention of treaties this president signed in his last term.
It's just a joke. A bad joke, but just a joke. Republicans are afraid to add Puerto Rico as a state for fear of it voting Democrat, they would never allow Canada to become a state even if you wanted to (or rather, 10 states), because they would never win an election again.
Canada isn't bound to the monarchy or to the UK. The king is just a figurehead, and the king's representative (the Governor General) is a powerless rubber stamp.
Now, to be clear, the (conceptual) figurehead is taken seriously. When the queen died, a great renaming happened, changing each province's court of queen's bench to the court of king's bench, Queen's Counsel are now called King's Counsel, and of course new currency is being minted with images of the king. But, none of that means the actual King Charles the person has any power at all.
The issue under Biden was protectionist/preferential policies which were challenged and got changed through the dispute mechanism[2]. The changed policy was then disputed again but the US lost the dispute[3].
The US has never gotten close to surpassing the tariff-rate quotas so the tariffs haven't applied.[4] Though the American dairy industry claims that's because of further protectionist policies.[5]
I'm not an expert on this so if you have more specific information please share sources.
America repeatedly threatened annexation and wanted water. It demands registration of goverment citizens. They call premier governor. Tariffs seem ti be preparatory steps meant to weaken Canada as a preparation for further attacks.
In general, conservatives are nowhere near to do the awful thing they say loudly they will do - and then, each time, they do that exact thing. Again again and again. These are plans and ignoring them is a self delution.
Also, multiple foreign countries like Russia are trying to make war right now.