Depends on what kind of breach and severity. Maybe if the the one breaching laws is harming people and refusing to stop, then maybe a sufficient amount of force by competent entities is required.

Can be, depending on circumstances and on the laws.

Yes

International Law is different from other aspect of law in that it’s a complex system of treaties and conventions and customs. It’s not a monolithic thing.

There question you posed can’t be answered at this level of abstraction.

No