These parts of the article provides plausible explanation:

"Brian Jenkins, an aviation-security expert at the Rand Corp., said the nature of the security measure suggested that it was driven by intelligence of a possible attack."

"The ban would begin just before Wednesday's meeting of the U.S.-led coalition against the Islamic State group in Washington. A number of top Arab officials were expected to attend the State Department gathering. It was unclear whether their travel plans were related to any increased worry about security threats."