ISLAMABAD, Pakistan — An American Qaeda operative was arrested in the sprawling southern city of Karachi in recent days by Pakistani security officials, Pakistani officials said Sunday. American and Pakistani officials said the man arrested was Abu Yahya Mujahdeen Al-Adam, who was described as having been born in Pennsylvania and who was thought to be affiliated with the operations division of Al Qaeda, commanding fighters in Afghanistan. Little else was known about him, American officials said, and it was not immediately clear that American officials were involved in the arrest. Initial reports seemed to have confused the American with Adam...
