US Air Force STAFF Sergeant Timothy Arnold, a member of the Air Mobility Command team, fires a M9 9mm pistol during the Pistol competition portion of Exercise DEFENDER CHALLENGE 2000 at Lackland Air Force Base, Texas. The Exercise is as annual Air Force wide competition, sponsored by Air Force Security Forces, which showcases the talents and capabilities of 13 international Security Forces teams in 7 physical fitness events, base defense, and policing skills over a period of 6 days