"In February 2014, Russia made several military incursions into Ukrainian territory. After Euromaidan protests and the fall of Ukrainian president Viktor Yanukovych, Russian soldiers without insignias took control of strategic positions and infrastructure within the Ukrainian territory of Crimea. Russia then annexed Crimea after an unlawful referendum in which Crimeans voted to join the Russian Federation, according to Russian official results.[12][68][69][70][71] In April, demonstrations by pro-Russian groups in the Donbass area of Ukraine escalated into an armed conflict between the Ukrainian government and the Russia-backed separatist forces of the self-declared Donetsk and Luhansk People's Republics. In August, Russian military vehicles crossed the border in several locations of Donetsk Oblast.[31][72][73][74][75] The incursion by the Russian military was seen as responsible for the defeat of Ukrainian forces in early September."