A large majority of all Boeing models are sold to outside the country, with Boeing being one of the nation's largest exporters. These same countries having a vested interest in Boeing because they build wings, tails, engines, etc. Is just part of marketing strategy. Airbus does the same. If Boeing was all American built, those sales would go to guess who?
I listen to Trumps speech live streamed at Boeing, and I have to be honest it was the worse speech I ever heard from a dignitary at Boeing. It was his usual stump speech from the campaign trail. Save American jobs, fine, we are good with that, but there was no mention of Airbus at all, who has been capturing market share away from Boeing and how they have been able to do that. Going global and lowering the cost of the airplane.