Armed men (L), believed to be Russian servicemen, stand guard outside Ukraine's naval headquarters after it was taken over by pro-Russian forces, as Russian naval officers (R) are seen in the background, in Sevastopol, March 19, 2014. Russian troops backed by unarmed volunteers stormed Ukraine's naval headquarters in the Crimean port of Sevastopol on Wednesday and raised the Russian flag, as Moscow tightened its control of the Black Sea peninsula. [Photo/Agencies]