Doesn't the history of war in the twentieth century (because we've got to start somewhere) suggest that "international law" means absolutely fucking nothing at

Doesn't the history of war in the twentieth century (because we've got to start somewhere) suggest that "international law" means absolutely fucking nothing at fucking all when it comes to major wars? Why bother? What are you going to do to enforce it, invade the guy who just nuked/invaded you/your friends?