In December 2009 the US government launched an air strike against the tiny Yemeni village of al-Majalah where al-Qaeda militants were believed to be in hiding. A second attack a week later targeted the prominent religious leader Anwar Awlaki. He escaped unharmed but many villagers were killed. These two strikes were intended to set back al-Qaeda's operations in Yemen but, within 24 hours, Umar Farouk Abdulmutallab - a 23-year-old Nigerian man and...