THE news last week that two Muslim military personnel, James Yee and Ahmad al-Halabi, had been arrested on suspicion of aiding Al-Qaeda prisoners at Guantnamo Bay (with another three Muslim servicemen under watch) seemed to prompt much surprise. It should not have. It has been obvious for months that Islamists who despise America have penetrated U.S. prisons, law enforcement, and armed forces. In February, a milestone Wall Street Journal article established that imams who consider Osama bin Laden "a hero of Allah" dominate the Islamic chaplaincy in the New York state prison system. In March, I documented the case of...