US Air Force SENIOR AIRMAN Ivin Osores, Air Force Space Command, fires his M16A2 rifle down range during the combat rifle competition at Camp Bullis, Texas, during DEFENDER CHALLENGE 2000. Defender Challenge is the annual Air Force wide competition sponsored by Air Force Security Forces. This competition showcases the talents and capabilities of 13 international Security Forces teams in seven physical fitness, base defense and policing skills over six days