"the system of international laws and treaties" are only effective to the extent that someone is going to enforce it, and that someone is the US and its allies. So ultimately it's military power that matters.

The status quo is only maintained because the US has military bases all over the world. If we retreat from the world and let Iran do whatever it wants (which is more influence and an Islamic empire), the the world order crumbles and that has an even more increased chance of WW3, as multiple nations will fight over the void left behind by the US.

Part of the reason things are unfolding this way is because the US rose to world power with the invention of the nuclear bomb.... which automatically means that toppling the US might mean nuclear war, which spells doom for the entire world. Not sure I would call that luck, but that is why the world cannot change to a new world order easily without existential risk. And as the "world police" the US doesn't want non-allies to get the bomb for this reason (something that Trump has been saying for years, which proves he is just maintaining status quo).