Book excerpt: Since 1990 offenders are more likely to be naturalized citizens, and to have foreign connections. Their espionage is more likely to be motivated by divided loyalties. Twice as many American espionage offenders since 1990 have been civilians than members of the military, fewer held Top Secret while more held Secret clearances, and 37% had no security clearance. Two thirds of Amer. spies since 1990 have volunteered. Since 1990, 80% of spies received no payment for espionage, and since 2000 it appears no one was paid. Six of the 11 most recent cases have involved terrorists, either as recipients of info., by persons working with accused terrorists at Guantanamo Bay, or in protest against treatment of detainees there. Illustrations.