Air Force Reserve Command Defender Challenge Team Members Tech. Sgt. Mariano Flores, Senior Airman Rick Cardona, and Tech Sgt. Francisco Gonzalez, navigate the “Tough Nut” obstacle at the Camp Bullis Military Training Reservation, Texas, Sept. 6, 2018. The team was training for the Defender Challenge competition. The challenge consisted of events designed to evaluate the team and individual in combat and defense skills.