A suicide attack on a Pakistani market Friday killed 20 people and wounded at least 40, according to officials. Among the dead were five members of local security forces and several children headed to school. A Pakistani Taliban spokesman took responsibility for the attack in a phone call to the Associated Press, saying, “This is revenge for killing our people.” Radical Islamic militants connected to the Taliban have killed thousands of Pakistanis in recent years, often conducting its operations in public spaces like markets or places of worship. In a cache of letters released Thursday that American commandos seized from Osama bin Laden’s Pakistan compound, terrorist leaders criticized leaders of the Pakistani branch of the Taliban for its attacks on innocent Muslims.