Royal Air Force Regiment Corporal Mark Holyday, apprehends US Air Force SENIOR AIRMAN Deryck Schnee during a simulated flight line intrusion in the Base Response event during DEFENDER CHALLENGE 2000 at Lackland Air Force Base, Texas. 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 24 events six days