In February and March 2014, Russia invaded the Crimean Peninsula of Ukraine, occupied it, and then annexed it after an illegitimate referendum. This took place amid the uncertainty that immediately followed Ukraine's Revolution of Dignity. The invasion marked the beginning of the Russo-Ukrainian war. Crimea's annexation has been described as an instance of modern Russian imperialism. It was the first time since World War II that a European country had annexed part of another, and some analysts see the annexation as the beginning of a Second Cold War between Russia and the West.
The events in Kyiv that ousted Ukrainian president Viktor Yanukovych on 22 February 2014 sparked both pro- and anti-separatist demonstrations in Crimea.