Trump is simply responding to the trade protectionists who voted him in. No different than our government responding to our voters - the dairy, poultry, eggs protectionists, the environmentalists who do not want to see more oil pipelines built, the security establishment who doesn't want a trade deal with China, the pensioners who don't want to allow privatized healthcare, the provinces who won't allow relaxed sales of alcohol and so on etc.  I think this is also one more way Trump is putting pressure on Canada to also fund its NATO commitments which we have  never done even though we agreed to it. Americans aren't the only ones with a significant protectionist anti-trade voter block, as we definitely have our share as well.