In return for this, states _must_ give up some of their sovereignty and implement a system of universal human rights within their borders to ensure justice for populations in conquered and occupied territories like northern ireland, hawaii, israel, others..
That, to my mind, is the fundamental bargain of international law and a rules based order.
If there is no bargain, you just get whatever you want, and everyone else can fuck themselves. That's not likely to be a fair, rules based, order.