Ironically GOP talks about European sovereignty over their own defense, but economically want to treat them like a vassal

If you think about it in terms of game theory that is actually a fair approach - you have an ally, you propose a best-case path forward for the alliance where both members are strong. If the ally don't want to take that path then you exploit the ally instead since a technically incompetent ally is a liability who needs to be kept under tight control.