Several hundred mines have drifted into the Black Sea after breaking off from cables near Ukrainian ports, Russia's main intelligence agency and shipping market participants said.The Black Sea is a major shipping artery for grain, oil, and oil products."Due to storm weather, the cables connecting the mines to anchors were broken," Russia's Federal Security Service (FSB), the main successor to the Soviet-era KGB, said in a press release dated March 19."Due to wind and water currents…