Hilary Clinton was half right. Putin's not just channeling Hitler but Stalin as well. He invaded a foreign nation claiming the need for Lebensraum, that he had the right to invade anywhere where Russians lived. At the same time, he's validating Stalin's ethnic cleansing of the natives. The reason there's a Russian majority, or any Russians at all, is clear. Katherine the Great invaded the Crimea to get a warm water port, holding the native Tatars and others under the Russian thumb. Then Stalin and Khrushchev decided to strengthen control by killing and evicting the natives, then moving in Russians. Many native came back at the fall of the USSR.
There's now a bare Russian majority. Of course, Putin doesn't care about anyone but his ego and covering for being in the closet, so he rigged an election claiming that over 90% of people under his military occupation chose to become part of Russia. He then invaded Ukrainian naval bases.
So what's the UN going to do? Absolutely nothing. Russia and China, totalitarian regimes, have veto power in the Security Council. They protect other dictatorships against encroaching democracy, so they certainly protect themselves. When non-democracies not only have a vote in the democratically run General Assembly but also have veto power, the UN can't ever live up to the goal it set for itself.
The US should pull out of the UN. It has some arms, such as UNICEF, that I'd support if they split off and became independent NGO's, but the UN's political body is, quite clearly, just a shelter for despots.