Attacks like the shooting spree last month in France by militant gunman Mohamed Merah are difficult to disrupt
Hooded police walk next to the building where self-professed Al-Qaeda militant Mohamed Merah was living, March 23, in Toulouse, southwestern France. Nearly a year after a US raid killed Osama bin Laden, his core Al-Qaeda network in Pakistan is "essentially gone" but its affiliates remain a threat, US intelligence officials said.