The difference is that Russia invading Ukraine is a clear-cut war between two independent states. Chechnya was/is a part of Russia, so the situation is the same as in China with Xinjiang and Tibet. And Yugoslavia was a complicated and bloody break-up of a federal republic (followed by the even more complicated and bloody break-up of Bosnia and the breaking away of Kosovo from Serbia). But the Russia-Ukraine war brings back memories of Hitler invading Poland, where the Germans also claimed to be acting in "self-defense" (https://en.wikipedia.org/wiki/Invasion_of_Poland#German_inva...).