Khalid Sheikh Mohammed, accused as the main plotter of 9/11 attacks, agrees to plead guilty

WASHINGTON — Khalid Sheikh Mohammed, accused as the main plotter in al-Qaeda’s Sept. 11, 2001, attacks on the United States, has agreed to plead guilty, the Defense Department said Wednesday, pointing to a long-delayed resolution in an attack that altered the course of the United States and much of the Middle East.