With an MP-5 submachine gun at the ready, STAFF Sergeant Marie Takeshita, 51st Medical Group takes cover behind a wall during the take-over of the 51st Fighter Wing Headquarters building during the Initial Response Readiness Exercise/Combat Employment Readiness (IRRE/CERE) exercise at Osan Air Base, Republic of Korea. The quarterly exercise tests the 51st Fighter Wing's ability to respond to combat situations