Russia's Black Sea fleet based in annexed Crimea has installed a new commander, RIA news agency cited sources as saying on Wednesday, after Russian military bases on the peninsula were rocked by explosions in the past nine days. If confirmed, the removal of the previous commander Igor Osipov would mark the most prominent sacking of a military official in the nearly six months since Russia launched its war on Ukraine. State-owned RIA said the new chief, Viktor Sokolov, was introduced to members of the fleet's military council in the port of Sevastopol.