I strongly doubt that Putin would ever nuke Ukraine. He wouldn't need to as he may very likely take over that country by simple military force. His threats of "nuking" are directed elsewhere. His beef with Ukraine is that the current Ukrainian president is far more democratic than the previous Ukrainian administration that was friendly to Putin and corrupt. The current Ukraine wishes they could join NATO and maybe the EU, in the future. That's a threat to Putin as it represents diminishing influence for him, and more democracy at his side door. If Putin "nuked" Ukraine (which again surely wouldn't happen), it would not be ignored as an "isolated incident". I very strongly disagree with you on that. I'm not sure where you derive that impression from. If Putin overtook Ukraine with an "Oh, well!" as the reaction by the US and/or Western and Central Europe, he would be emboldened to move further west and south. Hitler decided to invade countries in Europe, prior to and during WWII. He wanted to rule more and more places. Initially, little was really done to stop him. Some countries (like the US) were isolationists and "didn't really care so much". I'm sure most here remember that from high school World History class. Nazi Germany allied with Italy and eventually Japan. Putin has potential allies like China P.R.C. and other countries strongly leaning towards, on the possible verge of, or fully autocratic...and hungry for expansion. It's true we must be careful with people like Putin. It's a tough game, this international relations!

I now live in Czech Republic with my Czech husband. It sure would be rough having an American say that they didn't care if Putin invaded Czech Republic some day, because it was an "isolated conflict". Czechs are very concerned, despite being in the EU and a NATO country now. During WWII, they suffered like many in countries invaded by and controlled by Nazis. They also hated having the Russians force communism on them for so many decades. Dissent was roughly punished, propaganda was rampant, freedom and democracy gone. When there were major uprisings against the Soviets, tanks came in killing many, shooting buildings, and arresting many (and more). This was especially horrible in Hungary and Czechoslovakia. And there were worse atrocities. It's easy for people to deny and forget, unfortunately.