A Japan Coast Guard's vessel and U.S. military plane search for a Japanese fighter jet, in the waters off Aomori, northern Japan, Wednesday, April 10, 2019. The Japanese air force F-35 stealth fighter crashed into the Pacific Ocean during a night training flight and parts of the jet were recovered, the defense ministry said Wednesday. (Kyodo News via AP)
An Air Force A-10 warthog maneuvers next to mountains during a live fire exercises, as part of the annual US-Philippines joint military exercise at Crow Valley, in Capas town, Tarlac province, north of Manila on April 10, 2019. (TED ALJIBE/AFP/Getty Images)
A US Marine Amphibious Assault Vehicle (front) maneuvers while a seahawk helicopter hovers above the USS Wasp, US Navy multipurpose amphibious assault ship, during the amphibious landing exercises as part of the annual joint US-Philippines military exercise on the shores of San Antonio town, facing the South China sea, Zambales province on April 11, 2019. (Photo by TED ALJIBE / AFP) (Photo credit should read TED ALJIBE/AFP/Getty Images)
A-29 Super Tucano military aircraft fly over targets during a drill by the Lebanese Air force in the northern Lebanese village of Hamat on April 11, 2019. (Photo by Ibrahim CHALHOUB / AFP) (Photo credit should read IBRAHIM CHALHOUB/AFP/Getty Images)
Brazilian navy members inspect the riflescope of a firearm during the Defense and Security International Fair 2019 (LAAD 2019) at Riocentro Expo Center in Rio de Janeiro, Brazil, on April 02, 2019. (MAURO PIMENTEL/AFP/Getty Images)
Sudanese protesters flash the victory sign at a passing military vehicle as they rally for a second day outside the military headquarters in the capital Khartoum on April 7, 2019. - Sudanese police fired tear gas at thousands of protesters who rallied outside the army headquarters for a second day urging the military to back them in demanding President Omar al-Bashir resign. (AFP/Getty Images)
A soldier holds a machine gun as he patrols the Russian northern military base on Kotelny island, beyond the Artic circle on April 3, 2019. - The Russian military base dubbed the "Northern Clover", home to 250 soldiers on the island of Kotelny, beyond the Arctic Circle, is to serve as a model for future military installations in the Arctic, a strategic region for Moscow that continues to strengthen its presence with the new perspectives offered by global warming. (MAXIME POPOV/AFP/Getty Images)
Philippine Navy personnel take photos of an OV-22 Osprey military aircraft as they take part in the Joint US-Philippine Military Exercise flag dubbed "Balikatan 2019" Thursday, April 11, 2019, off San Antonio, Zambales province northwest of Manila, Philippines. The amphibious exercise, facing the disputed Scarborough Shoal in the South China Sea, involves hundreds of Philippine and American troops to hone their skills in "tactics, techniques and procedures." (AP Photo/Bullit Marquez)
A soldier of the German Bundeswehr secures a Tactical Operations Center during the Allied Spirit X international military exercises at the U.S. 7th Army training center on April 9, 2019 near Hohenfels, Germany. Approximately 5,600 soldiers, including around 1,300 from the U.S. and the rest from Denmark, Finland, Germany, Israel, Italy, Lithuania, Moldova, Netherlands, Poland, Slovakia, Spain, Sweden, Turkey, and the United Kingdom are taking part in the nearly three-week long exercises. (Photo by Lennart Preiss/Getty Images)
A Philippine Air Force OV-10 plane drops a bomb at its target during the Joint U.S.-Philippine Military Exercise flag dubbed "Balikatan 2019" Wednesday, April 10, 2019 at Crow Valley, Capas township, Tarlac province north of Manila, Philippines. About 8,000 Philippine and American troops are taking part in the two-week exercise that focuses on "territorial defense" among the two militaries. (AP Photo/Bullit Marquez)
A Philippine Navy band plays as the Russian anti-submarine ship Admiral Tributs prepares to dock during the ship's arrival at the international port in Manila on April 8, 2019. - Russian anti-submarine ships Admiral Tributs and Vinogradov, including the sea tanker Irkut, arrived in Manila on April 8 as part of a goodwill visit. (TED ALJIBE/AFP/Getty Images)
A Russian military helicopter Mi-26T2V flies during an exhibition flight at the Mil Moscow Helicopter plant outside Moscow on April 3, 2019. - The largest in the world, the Mi-26T2V has completed its preliminary flight tests and will be handed over to the Russian Defence Ministry for official military tests. (YURI KADOBNOV/AFP/Getty Images)