By David Ljunggren, Enas Alashray and Hatem Maher WASHINGTON/CAIRO, July 18 (Reuters) - The U.S. military said on Saturday two of its personnel were killed in Jordan and another was missing after an Iranian attack, while Iran's supreme leader said Washington would pay for "seeking to incite war" after a seventh straight night of U.S. strikes. The U.S. and Iran have intensified attacks since an interim ceasefire deal signed a month ago fell apart last week, raising the possibility of a return to all-out war.