Chief of Staff of the U.S. Air Force Gen. Mark A. Welsh III and British Royal Air Force Chief of the Air Staff, Air Chief Marshall Sir Andrew Pulford answer questions during a press conference hosted during the Trilateral Exercise at Langley Air Force Base, Va., Dec. 15, 2015. The exercise, which aims to give coalition forces an opportunity to hone skills during simulated adversarial scenarios, kicked off Dec. 2, 2015 and is scheduled to conclude Dec. 18, 2015. (U.S. Air Force photo by Tech. Sgt. Katie Gar Ward)