Col. Charles S. Kohler, a spokesman for the Guard, confirmed that the aircraft were taking part in the battle but declined to provide any further details for security reasons. A dozen A-10s and 280 airmen from the Guard's 104th Fighter Squadron deployed to the Middle East last week, just days before the fight to retake Mosul began. The planes are scheduled to be retired in 2020 and the deployment to fight the Islamic State could be their last.