U.S. Air Force F-15E Strike Eagle pilots and weapon systems officers assigned to the 391st Fighter Squadron at Mountain Home Air Force Base, Idaho, step to their aircraft during ATLANTIC TRIDENT 17 at Joint Base Langley-Eustis, Va., April 18, 2017. The U.S., France, and the U.K., the three countries participating in AT17, began building a relationship during WWI that has lasted 100 years. (U.S. Air Force photo/Airman 1st Class Anthony Nin Leclerec)