The notion that current allies become enemies simply because they become required to pay a fair share of their defense is a dumb one. But if true, questions how allied such regions really were, if their allegiance can be bought or disbanded by a few dubloons.
So I guess you haven't noticed Trump's very-thinly-veiled threats of military action against Greenland, Canada, and Panama. People in those countries, and Europe, have definitely noticed.
OK, I see it like this: you can set boundaries with your friends. Setting boundaries with friends doesn't make them enemies, that's dumb.
If you're a country, reserving the right to use military force is a way of setting boundaries.
Think of it like this, your friend Darald never pays for anything and expects you to foot the bill for all group activities, and even pay his rent and deal with his crazy ex-wife (paying his alimony, etc). Darald also talks shit about you every chance he gets, in front of your other pals. You eventually get fed up with enabling his destructive / lazy behavior and stand up for yourself. Do you: a) punch him in the nose; b) use court action to seize his assets to recoup some of your losses; c) go to his house and take the money he owes you out of his mattress, and push him off you when he tries to stop you; d) all of the above; e) do nothing, keep letting yourself get abused.
The notion that current allies become enemies simply because they become required to pay a fair share of their defense is a dumb one. But if true, questions how allied such regions really were!