US Air Force SENIOR AIRMAN Shawn Partington (Right), Air Combat Command, fires at targets during the Combat Rifle Competition at Lackland Air Force Base, Texas, in support of DEFENDER CHALLENGE 2000 on October 31st, 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 events, base defense, and policing skills over six days