re: Lawfare: how is this defined, and how can it be (legally) stopped?

Lawfare is using existing law to achieve a governmental or military objective.

It’s no different from what lawyers have done for ages. Find a statue or precedence that supports your position, and use it to your advantage.

Courts exists to make judgement calls on who is right, or more likely when it comes to lawfare in the context you are using it in, international opinion will dictate who is right and who is wrong.