A group of Islamic State militants penetrated an Iraqi air base where U.S. military advisers are training Iraqi forces, the first time attackers have gotten beyond the outer perimeter of an Iraqi base being used by American trainers.

U.S. officials said eight Islamic State militants struck a small building at the edge of the huge al-Asad Air Base before being repelled by Iraqi forces. All eight were killed.

Military officials said American and other coalition trainers were “several kilometers” away from the attack and under no direct threat. There are 400 U.S. Marines and other service members at the base. […]