No one claims responsibility for the attacks in Karachi that injure 65; however, shrines and mosques belonging to adherents of doctrines opposed by militants have been frequent targets of the Pakistani Taliban.Two suicide bombers attacked crowds of Pakistanis visiting a Sufi Muslim shrine in the country's largest city, Karachi, Thursday night, killing at least 10 people and wounding 65 others in an attack that reminded the nation of extremists' ability to strike virtually at will.