US Air Force (USAF) SENIOR AIRMAN (SRA) Steven Melling, shoulders his 5.56mm M16A1 rifle equipped with Multiple Integrated Laser Engagement System (MILES) after firing at Opposition Forces (OPFOR) during the Security Forces tactics competition conducted at Vandenberg Air Force Base (AFB) California (CA), during Exercise GUARDIAN CHALLENGE 2002. Guardian Challenge, a four-day space and missile competition, is hosted annually at Vandenberg AFB, CA to test the wartime readiness of Air Force Space Command (AFSPC) professionals