The ONLY thing that gives the UN any authority in its' resolutions now is US military might. Without us, they have no teeth. And for any other military to step into that vacuum would place them in opposition to us should we get out of the UN.
Do you see any takers for that position on this planet right now? I didn't think so.
Russia, China, the EU, none of them have the ability to project power on any scale outside of their borders. The US is the ONLY nation on Earth who has military transport of any scale whatsoever. We're in the driver's seat - let's go somewhere. Without the UN parasites.