MOSCOW – A Russian oil tanker split in two during a fierce storm early Sunday, spilling some 560,000 gallons of fuel into a strait leading to the Black Sea in one of the worst environmental disasters in the region in years, authorities said. Two freighters carrying sulfur also sank nearby in the Strait of Kerch, a narrow strait linking the Black Sea and the smaller Sea of Azov to the northeast, said Sergei Petrov, a spokesman for the regional branch of Russia's Emergency Situations Ministry. Operations to rescue the crews of all three ships were under way, officials said. The...