You already knew the United Nations was worthless, but you can never know enough about why. We've reached an age when a lot of people think distrust of multinational organizations like the UN amounts to "white nationalism" or something. That's what they think is behind Brexit. If Brits want their own country to determine its own destiny, it must be because they don't like brown people, I guess.
In actual fact, multinational organizations are almost completely incapable of taking effective action to solve a problem, because there is always someone around who doesn't want the problem solved and has veto power. Nowhere is this more true than the United Nations, which actually had a chance yesterday to deal a serious blow to the viability of the murderous Kim regime in North Korea.