The security warning level at the U.S. Al Udeid Air Base in Qatar has been reportedly lowered, three sources briefed on the situation told Reuters on Thursday. This came after some personnel were advised to leave the base on Wednesday amid rising fears over a possible U.S. attack on Iran.One source told Reuters in the latest report that the U.S. aircraft moved out of the military base are gradually returning. Doha and Washington have yet to comment on the matter.Al Udeid Air Base, the largest U.