Out of Captivity

When U.S. officials at Guantanamo Bay reviewed a list of prisoners in March, they decided to send Abdullah Mesud home. Although the 29-year-old Pakistani had been arrested in northern Afghanistan while fighting for the Taliban, he was hobbled by an artificial leg and judged to be a low security risk, according to Pakistani officials who supervised his release.

Letting him go was a fatal error. Upon returning to Pakistan's lawless Waziristan region, Mesud rallied tribesmen and former Taliban fighters to hit back at the U.S. and its ally, Pakistan President Pervez Musharraf. On Oct. 9, as Mesud later...