ENEMIES

Bill Gertz, defense and national security reporter for The Washington Times, describes the threat posed by foreign agents and terrorists who exploit U.S. weaknesses in three excerpts from his new book, “Enemies: How America’s Foes Steal Our Vital Secrets — And How We Let It Happen” (Crown Forum).

Monday: The U.S. government and the law fail to stop China from getting its hands on highly sensitive Navy technology.

Tuesday: A spy for North Korea recruits a “disciple” to steal secrets in Washington - and gets two years.

Wednesday: The U.S. has struggled to infiltrate al Qaeda and other deadly Islamist groups.