What we’re seeing here is Trump’s negotiating style in action: bully, bluster and threaten. While these are useful tools to have at hand, they are much less effective when used against our supposed allies. I’m also not convinced this administration’s toolbox contains any other tools, to be frank.
I agree that NATO members should meet the terms to which they have agreed, but then I also think the US ought to pay its UN dues and that Trump ought to pay all those people he stiffed the money he owes them. None of which is likely to happen any time soon.