Moderate Syrian rebels, once they are made battle-ready by a U.S.-led coalition, may be asked to help restore the border between Syria and Iraq that Islamic State group militants have effectively wiped out, the top American military official said Thursday.

Army Gen. Martin Dempsey cautioned, however, that it may be a year before the Syrian rebel force that President Barack Obama calls a key element of his strategy for destroying the Islamic State group is ready for action.

“We think if we can restore the border, it goes a long way to beginning to put the kind of pressure on ISIL that will lead to its ultimate defeat,” Dempsey, chairman of the Joint Chiefs of Staff, said, using a common acronym for the group that U.S. intelligence officials estimate has up to 31,000 fighters. […]