Watch: Huge flames and thick, dark smoke rise from Crimea oil tankSocial-media footage showed flames billowing from the site in Sevastopol, Crimea's main city, early on Saturday. The Crimean peninsula, which was annexed by Russia in 2014, is home to the main naval base for Moscow's Black Sea Fleet. The attacks come as Ukrainian forces say they are ready to launch a military offensive with new equipment supplied by Western allies