"The biggest flaw in the UN system was that governments came to the UN and paid lip service to the tenets of the UN Charter but were unprepared to do what it took to patrol the global commons" - Samantha Power, in Chasing the Flame.
I'm still nowhere near done with Chasing the Flame, but it's an absolutely fantastic book, and I am increasingly drawn in by revelations of what should be obvious. This time, it's that the UN exists for international commons, rather than as a form of world government. The UN then does not supplant order, but it institutes it where none has exists, and where it is in the benefit of the whole international community for there to be order. The obvious commons are international waters, outer space, and Antarctica (the internet?). The more interesting interpretation of this commons is that nations where sovereignty collapses and areas where violence threatens to spill beyond borders are also an international stability concern and an international domain. Great stuff.