He won't. The defense industrial complex of the United States, that made more than 300 billion last year, is not going to let him. I think if we add direct and indirect, it will be more than half a trillion for the year.
There are a ton of GOP mega-donors who are shareholders of these mega companies. They will not let Trump move. In fact, they will be the biggest threat to the formation of the EU army. THat is what the recommendation to keep it extremely small at the start. Just Uk-Germany-France will be enough to get rolling. Once they start, they wont be able to stop. But of they go big, the option to mess up will always be there.