WASHINGTON, April 27 — In January 2002, George J. Tenet, the man who oversaw all American spy agencies, was asked by a visiting Italian intelligence official what he knew about United States officials making contact with exiled Iranian opposition figures. “I shot a look at other members of my staff in the meeting,” Mr. Tenet writes in his newly published memoir. “It was clear that none of us knew what he was talking about. The Italian quickly changed the subject.” The embarrassed Mr. Tenet, then director of central intelligence, had stumbled upon a quixotic effort by a few Pentagon officials...