The United States will in the coming days ask a U.N. Security Council committee to impose sanctions on seven ships suspected of violating U.N. sanctions on North Korea, a U.S. State Department official said on Monday. The seven vessels have illegally exported North Korean coal and iron ore to China, which traditionally earns Pyongyang between $200 million and $400 million a year, said the U.S. official, speaking on condition of anonymity. "These nominations are not just bureaucratic exercises.