Masked Protection Marines and airmen work together at a simulated contamination control area as part of the Vigilant Ace 17-1 exercise at Osan Air Base, South Korea, Nov. 17, 2016. Vigilant Ace is a biannual, bilateral training event where U.S. and South Korean service members conduct interoperability exercises. Marine Corps photo by Lance Cpl. Jacob A. Farbo SHARE: Download: Full Size (0.7 MB) Tags: Marines, Airman, Air Force, Marine Corps Credit: Lance Cpl. Jacob Farbo VIRIN: 161117-M-HD015-0054.JPG Photo Gallery