WASHINGTON, Feb. 22 - An American student who was imprisoned in Saudi Arabia for the last 20 months was returned to the United States and accused by the Justice Department on Tuesday of plotting with members of Al Qaeda in 2003 to assassinate President Bush. In an indictment unsealed in federal court in Alexandria, Va., the student, a 23-year-old American citizen named Ahmed Omar Abu Ali, is charged with providing material support for terrorism. Mr. Abu Ali is accused of training with Al Qaeda overseas and wanting to "become a planner of terrorist operations" like Mohammed Atta or Khalid Shaikh...