The UN never stopped a war. It was the fear of war that kept nations in check. No fear means more war.
The Useless Notions has actively CAUSED strife around the globe.
The UN should have died on 30 June 1950. But the Soviets were boycottong the Security Council and did not veto the resolution to resist Kim’s invasion of the South. Had they then everyone would have seen the UN for what it was, a fancy pants debating society where representatives get to enjoy the high life of Manhattan.