Crimea has historically been part of various empires and was part of Ukraine from 1954 until its annexation by Russia in 2014. Russia had been promoting a "Russian world" idea in Crimea for years prior to annexation through various civil organizations and influencing authorities. In early 2014, Russian forces seized control of the Crimean parliament and blockaded Ukrainian military units in Crimea. A referendum was held and Crimea was annexed by Russia in March 2014, demonstrating a new era of hybrid warfare involving information and psychological operations.