At this stage it literally makes no difference whether America is in NATO or whether America is out of NATO, they both at this moment in time mean the exact same thing, it's pretty damn obvious under Trump that America won't honour any NATO commitments, it's fine to say he can't leave NATO without approval of Congress but that's irrelevant, it doesn't mean he needs to respond to NATO's call for help. America is done in NATO under Trump, they're basically opening the door wide open and saying to Russia "Come on in, we won't do fuck all about it"