U.S. Marines with 2nd Air Naval Gunfire Liaison Company assist forward observer teams from the British Royal Army while conducting live-fire missions as part of Exercise Green Cannon 18 at Salisbury Plains, United Kingdom, July 4, 2018. Green Cannon is an annual live-fire exercise between the United States Marine Corps, allied and partner nations in order to increase interoperability in the region. (U.S. Marine Corps photo by Cpl. David Delgadillo) - U.S. Marines with 2nd Air Naval Gunfire Liaison Company assist forward observer teams from the British Royal Army while conducting live-fire missions as part of Exercise Green Cannon 18 at Salisbury Plains, United Kingdom, July 4, 2018. Green Cannon is an annual live-fire exercise between the United States Marine Corps, allied and partner nations in order to increase interoperability in the region. (U.S. Marine Corps photo by Cpl. David Delgadillo)