U.S. service members of the 36th Contingency Response Group, Andersen Air Force Base, Guam, and Marine Wing Support Squadron 172, Camp Foster, Japan, fuel a 67th Fighter Squadron F-15 Eagle during exercise Tropic ACE Sept. 1, 2017, at Kadena Air Base, Japan. Tropic ACE was designed to exercise components of Pacific Air Forces’ Agile Combat Employment (ACE) concept of operations (CONOPS), a warfighting concept the command is operationalizing to ensure airpower resiliency. (U.S. Air Force photo/ Airman 1st Class Greg Erwin)