I think it depends on how you explain the history and structure of the UN. One one hand, eh, maybe the UN was just enough for the US and USSR to hold off launching nukes. On the other hand, they may look at the structure with the US and USSR/Russia being permanent security council members (or the idea of permanent members in general) self defeating since we are often opposed and the UN can't really do much without the sign off from the Security Council. So they may say, the UN isn't an argument against because the UN is badly structured designed to not have any real teeth in the first place.
> the UN can't really do much without the sign off from the Security Council.
Yes, it can; it has deployed peacekeeping missions without Security Council signoff (UNEF I), by the UNGA after France and the UK vetoed action in the UNSC, it adopted broad sanctions against South Africa, through the UNGA, after a triple veto by the US, UK. and France.
The UNGA has taken various action, including expelling Russia from the Human Rights Council, in respect to the Russo-Ukrainian war in a process starting with a Russian Security Council veto.
The common underlying factor in all of these is the UNGA “Uniting for Peace” resolution pit forward by the US during the Korean War because, while dodged initially in that situation because of the Soviet boycott of the UN over other issues, the problem with letting the Security Council veto be the end of the story was made very clear in that context.
I'll amend my statement then. The UN has no teeth against big players. The UN has done some things, but they tend to be with smaller nations without as much clout on the world stage. The UN, still has yet to really wrangle in the major powers on the world stage. The UN wasn't really effective in preventing US wars in the middle east (Afghanistan and Iraq), isn't really effective in the currently unresolved situation in Ukraine, nor is it effective in wrangling in China's territorial claims or their tensions with Taiwan. The US refuses to allow the UN's International Criminal Court to oversee war crimes committed by US troops, as I suspect the same is true for Russia. Or has it been effective in negotiation in the Israel-Palestine relationship. Nor, as a guess, will the UN do anything mention-able in easing China-US relations. It would be better to say, mutually assured destruction has probably done more to wrangle in world powers than the UN has. And the UN's structure is such that it ultimately will never really be able to reign in world powers.
