In 2014, Russia made several incursions into Ukrainian territory. Beginning with Crimea, Russian soldiers without insignias took control of strategic positions and infrastructure within the Ukrainian territory of Crimea, which Russia annexed after a disputed referendum. Subsequently, demonstrations by pro-Russian groups in the Donbass area of Ukraine escalated into an armed conflict between the Ukrainian government and separatist forces of the self-declared Donetsk and Lugansk People's Republics. In August, Russian military vehicles crossed the border in several locations of Donetsk Oblast The incursion by the Russian military was seen as responsible for the defeat of Ukrainian forces in early September.