A preliminary Pakistani investigation has concluded a missile destroyed the airplane in which President Mohammed Zia ul-Haq and U.S. Ambassador Arnold Raphel were killed Aug. 17, it was reported Monday. The Washington Times quoted an unidentified senior Defense Department official as saying the preliminary conclusions of the Pakistani air force investigation that the U.S.-made C-130 transport was downed by a ground-to-air missile had not been endorsed by a U.S. team aiding in the investigation. The plane crashed while returning Zia, Raphel and 27 others, including U.S. Gen. Herbert Wassom, to Islamabad after they had witnessed a demonstration of U.S. military equipment. All aboard were killed. The Times quoted the senior official as saying the Pakistani conclusions were based on two factors: Had there been an explosion caused by a bomb planted aboard, the debris would have been scattered over a wider area; and no evidence could be found of any mechanical difficulties before the crash occurred.