The U.S. agency that operates the National Weather Service said on Wednesday four of its websites were hacked in recent weeks, becoming the latest federal agency to fall victim to a cyber attack. The breach follows a string of attacks on government agencies including the White House, Office of Personnel Management and one of its main contractors, USIS, which performs background checks on U.S. government employees. The Washington Post reported that Chinese hackers were behind the NOAA attack, citing unidentified officials. The report said NOAA was forced to seal off data on disaster planning, aviation, shipping and scores of other uses. NOAA had a data breach last month when an agency employee in Ohio was charged with stealing sensitive information from a federal database for the nation's dams and lying about the breach to federal agents.