The Islamic State group claimed responsibility on Tuesday for a weekend attack at a center near Dallas, Texas, exhibiting cartoon depictions of the Prophet Muhammad. An audio statement on the extremist group’s Al Bayan radio station said that “two soldiers of the caliphate” carried out Sunday’s attack and promised to deliver more in the future. The statement did not provide details and it was unclear whether the group was opportunistically claiming the attack as its own. It was the first time the Islamic State, which frequently calls for attacks against the West, had claimed responsibility for one in the United States. Two suspects in Sunday’s attack in the Dallas suburb of Garland were shot dead after opening fire at a security guard outside the center.