One could view the US defense budget as a sort of subsidy to Europe and Democratic Asia. If the US decreases its defense budget (by a lot), Europe will likely have to increase theirs.
Yes, and in return us Europeans agree to spend the vast majority of that budget on US arms. I'm thinking of multi-billion dollar nuclear subs and $100m aircraft. Then we allow tax free access to our markets and allow the US to skim a charge off all of our payments. To me that is the naivety of the Trumpist policy on Europe, it is only looking at the costs.