India, Jan. 8 -- Relations between the United States and Russia have sharply worsened after American forces took control of a Russian-flagged oil tanker in the North Atlantic. The ship, now named Marinera, was seized by the U.S. Coast Guard and Navy, leading to strong protests from Moscow, which says the action violates international law.

Russia's Transport Ministry confirmed that the tanker had been taken. Its Foreign Ministry accused the United States of breaking the United Nations Convention on the Law of the Sea and demanded that Russian nationals onboard be sent back home immediately.

After the seizure, Russia warned Washington not to mistreat its citizens and demanded their immediate return. Moscow also said the ship had legally s...