One of the major threats to peace after the breakup of the Soviet Union involved the Ukrainian region of Crimea, a peninsula extending into the Black Sea that been transferred by Khrushchev from the Russian Federation to Ukraine in 1954, where it was also the site of the main base of the Soviet Black Sea naval fleet. After the breakup of the USSR, many majority Russian-speaking citizens of Crimea sought to leave Ukraine and return to the Russian Federation, and other tensions arose due to the return to the region of Crimean Tatars, an ethnic minority who had been deported to Central Asia by Stalin during World War II. The OSCE High Commissioner on National Minorities became active, using a method called “seminar diplomacy,” which eventually led to an agreement to grant Crimea deep autonomy within Ukraine and to divide the Black Sea fleet between Russia and Ukraine. An OSCE “Project Coordinator” from the Conflict Prevention Centre assisted stabilizing the situation until Russia intervened militarily in 2014 and took full control of Crimea contrary to its agreement with the OSCE, an action that the OSCE was unable to prevent.