Obviously, you are right. Not everything is moving according to the formal and legal lines of international laws. But, despite this, the world has seen a dramatic decline in nuclear production. At one stage there were enough nuclear warheads to destroy this world completely. Undoubtedly, International system still runs on lopsided wheels but at least things have been labelled with their legitimate names. How far would the violation of laws stretch in this globalised world? Not today but yesterday we could have been invaded by a superpower state without their having legitimate cause to invade, irrespective of looking for fabricated justifications.
Well, the main cause behind this manipulation of established laws still remains thirst of power and hegemony. Sometimes I wonder if really cold war ended in 1991 or it just shifted to another track with a new version of strategies and tactics.