The Russians block in the Ukrainian navy

Not that the Ukrainian navy posed a real threat to the Black Sea Fleet, for good measure, the Russian navy scuttled a ship to block the fleet of Ukrainian frigates. It could be this is an attempt to force the Ukrainians to hand over the ships to the Russiansas much as it is an attempt to take over the naval base. 

http://www.dailymail.co.uk/news/article-2574567/EU-leaders-hold-emergency-summit-discuss-response-Russias-Crimean-invasion-ousted-Ukrainian-president-Yanukovych-assets-frozen-alleged-embezzling.html