US Air Force Technical Sergeant John R. Krayeski, kneeling, and SENIOR AIRMAN Frank W. Zenteck, both from team Air Mobility Command, prepare to engage on targets down range in their chemical gear during a simulated gas attack for a Combat Weapons event during DEFENDER CHALLENGE 2000 at Lackland Air Force Base, Texas, on October 31st, 2000. TSGT Krayeski aims a M16 rifle with a M203 Grenade Launcher attached. 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 seven physical fitness events, base defense, and policing skills over six days