Officials believe this is a new strategy from ISIS to organize attacks on nations in airstrike coalition . The U.S. has been bombing ISIS-held territory for more than two years and the group continues to hold territory. U.S. sources tell CNN that they knew of planned attacks and shared information with Belgians .
Officials believe this is a new strategy from ISIS to organize attacks on nations in airstrike coalition . Counterterrorism official tells CNN that terrorists killed in Belgium raid had ties to ISIS . U.S. sources tell CNN that they knew of planned attacks and shared information with Belgians .