Months of attacks by unmanned US predator aircraft have caused carnage among the middle ranks of terrorist leaders in the lawless lands along the border with Afghanistan, where al-Qa'eda remains dangerous despite suffering a serious defeat in Iraq. Their victims have included experienced Arab leaders and, it is now thought, Adam Gadahn, a former heavy-metal fan and so-called "killer computer nerd" originally from California. Nothing has been heard from him for months, leading intelligence experts to conclude that he may be dead. Mr Gadahn has been credited with helping transform al-Qa'eda's al-Sahab propaganda wing into a slick operation which communicates...