The U.S. targeted Taliban leader Mullah Mansour in an airstrike Saturday near the Afghanistan-Pakistan border, the Defense Department said, and a U.S. official said Mansour was believed to have been killed. Pentagon press secretary Peter Cook said the U.S. was still studying the results of the attack, essentially leaving Mansour's fate uncertain. But one U.S. official said Mansour and a second male combatant accompanying him in a vehicle were probably killed. President Barack Obama authorized the attack, which occurred on the Pakistani side of the border, and was briefed before and after it was carried out, a White House aide said. Both officials spoke on condition of anonymity and...