You think the boundaries weren’t spelled out? I mean, we all know “international law” is a joke 1st world countries ignore versus their own actions and the rest of the world, but versus eachother? “Don’t fuck with us and we won’t fuck with you” is stupidly over-defined.

The same for the financial enmeshment that sees this threat well-inside the realm of potential reality. Europe never promised not to sell these debts. The fact the US can’t complain about it if they do is part of what makes it a good threat. Are you not familiar with “soft power”, like, at all?