Distant Frontier
U.S. Air Force and Marine Corps aircraft prepare to conduct flight operations during exercise Distant Frontier at Joint Base Elmendorf-Richardson, Alaska, May 23, 2017. Distant Frontier is a unit-level training iteration designed to sharpen participants' tactical combat skills and develop interoperable plans and programs across the joint force. (U.S. Marine Corps photo by 1st Lt. Melissa M. Heisterberg)