Two F-15E Strike Eagles wait to receive fuel from a KC-135R Stratotanker during exercise Red Flag 15-1 on their way to Nellis Air Force Base, Nev., Jauary 23, 2015. The F-15s are assigned to the 4th Fighter Wing. U.S. (Photo by Airman 1st Class Aaron J. Jenne/Reuters)

Ministry of Defence handout photo of Chinooks from RAF Odiham as they take part in the Royal Air Force flypast over central London to mark the centenary of the RAF on Tuesday, July 10, 2018. (Photo by SAC Pippa Fowles (RAF)/PA Wire)

A Sudanese man plays a local music instrument ahead of a meeting with Mohamed Hamdan Dagalo, also known as Himediti, deputy head of Sudan's ruling Transitional Military Council (TMC) and commander of the Rapid Support Forces (RSF) paramilitaries, in the capital Khartoum on June 18, 2019. (Photo by AFP Photo/Stringer)

Pfc. Sebastian Rodriguez, machine gunner, Weapons Platoon, Lima Company, 3rd Battalion, 3rd Marine Regiment, Marine Rotational Force – Darwin, fires an M240 machine gun during a night squad-attack exercise, here, May 22, 2013. (Photo by Sgt. Sarah Fiocco/U.S. Marines)

Spectators cheer as the United Launch Alliance Delta 4-Heavy rocket, with NASA's Orion spacecraft mounted atop, lifts off from the Air Force Station, December 5, 2014, in Cape Canaveral, Fla. (Photo by Smiley N. Pool/AP Photo/Houston Chronicle)

A person tries to extinguish flames as sparks fly during a wild forest fire in Valparaiso, Chile, Sunday April 13, 2014. Authorities say the fires have destroyed hundreds of homes, forced the evacuation of thousands and claimed the lives of at least seven people. (Photo by Luis Hidalgo/AP Photo)

Del Mar firefighters roll up hose after a day fighting wildfires Wednesday, May 14, 2014, in Carlsbad, Calif. More wildfires broke out Wednesday in San Diego County, threatening homes in Carlsbad and forcing the evacuations of military housing and an elementary school at Camp Pendleton. (Photo by AP Photo)

Beachgoers watch the detonation of a 500 pound British bomb on the beach on May 19, 2014 in Wassenaar, Netherlands. The bomb was dropped by the British allied forces during the second world war over nearby Leiden where it was found on a building site. (Photo by Michel Porro/Getty Images)