Lightning Strike
Russia took control of Crimea with fewer than 20,000 soldiers. They rolled in with almost no opposition, and when the dust had settled, Crimea “belonged” to Russia again.
This is how it went down.
Pro-Russian demonstrations erupted in the port city of Sevastopol in February 2014. Anonymous Russian troops (not very many) swooped in and took control of government and media infrastructure. Then, with very little opposition, they took over all the main centers in the peninsula and installed a pro-Russian administration under Sergey Aksyonov. By the end of March, there had been a referendum on incorporation into Russia (Yes, yes, yes, said everybody), and sweet as a nut, the “Republic of Crimea'' and the “Federal City of Sevastopol'' were federal partners/subjects of Russia. Putin rejects the label “annexation”—as he tells it, Russia won fair and square on overwhelming public opinion. Minnesota separatists should be glad to hear this—all they need to do is win a state-wide referendum of separation.
The USSR was taking shape once again. Putin threatened nuclear action, and everybody piped down. Nuclear deterrence deterred the invaded from protesting, and discouraged anybody from trying too hard to rescue Crimea from the Iron Wolf.