Europe

Pretending that the referendum didn't have a shred of credibility is the height of intellectual dishonesty. Let's just look at a few facts about Crimea from a US government study. First thing to note is that it was never part of Ukraine proper. US government referred to it as the Autonomous Republic of Crimea. Second thing to note is that majority of the people in Crimea do not consider themselves Ukrainian, and the biggest demographic considers themselves Russian:

Furthermore, we can take a look at a few slides from this lecture that Mearsheimer gave back in 2015 to get a bit of background on the subject. Mearsheimer is certainly not pro Russian in any sense, and a proponent of US global hegemony. First, here's the demographic breakdown of Ukraine:

here's how the election in 2004 went:

this is the 2010 election:

As we can clearly see from the voting patterns in both elections, the country is divided exactly across the current line of conflict. Furthermore, a survey conducted in 2015 further shows that there is a sharp division between people of eastern and western Ukraine on which economic bloc they would rather belong to:

Finally, here's what the regime in Ukraine has been doing to the people in these areas as reported by CNN in 2014, I'm really curious how you're going to justify why those people should've just obeyed the regime after watching that

https://twitter.com/paulius60/status/1611148483859255296