The Qatar government in the mid-1990s invited al Qaeda operative Khalid Sheikh Mohammed and his family to live in Qatar, the 9/11 commission found. Mr. Mohammed was given a job at the Qatar Ministry of Electricity and Water. At the time, Mr. Mohammed was under indictment in the Southern District of New York for his role in a plot to blow up U.S.-bound jetliners. He was also wanted for questioning in connection with the 1993 World Trade Center bombing. In 1996, FBI agents arrived in Qatar to arrest Mr. Mohammed. But the Qataris resisted handing him over, and Mr. Mohammed...