@RJnomore1
My own extremely inadequate understanding was that the UN was set up to stop there ever being a ww3 and so I’m a bit surprised to find it toothless here… as you can see I know very little though.
No you are right, it was set up for just that, and it relies on nations working together to come to diplomatic resolution and a forum of discussion to talk about what can be done to prevent war.
But when one country goes rouge, there isn't much it can do.
Now just because NATO and the UN can talk about it, and say we can't do anything, nobody do anything. There isn't anything in reality stoping nations from disagreeing with either and doing what they want. UK and USA did this when they decided to go in to Iraq I believe. They went against "better judgment".
However, I genuinely hope nobody decides "fuck it I'm going in to Ukraine" because that will be the straw that breaks the camel's back and we will have a Cuban missile crisis stand off.