German troops in Stalingrad, USSR. September 10, 1942. (Photo by TASS)

Mave Grace, 11, who had part of her arm chopped off by militiamen when they attacked the village of Tchee, stands with her sister Racahele-Ngabausi, aged two, in an Internally Displaced Camp in Bunia, Ituri province, eastern Democratic Republic of Congo, April 12, 2018. (Photo by Goran Tomasevic/Reuters)

Mil Mi-8 combat helicopter flies over Moscow, Russia on May 7, 2019 during the dress rehearsal of a Victory Day air show marking the 74th anniversary of the victory over Nazi Germany in the 1941-1945 Great Patriotic War, the Eastern Front of World War II. (Photo by Sergei Savostyanov/TASS)

Brazilian actress Julia Stockler (L) and Brazilian actress Carol Duarte kiss while posing with Brazilian film director Karim Ainouz during a photocall for the film “A Vida Invisivel de Euridice Gusmao (The Invisible Life of Euridice Gusmao)” at the 72nd edition of the Cannes Film Festival in Cannes, southern France, on May 20, 2019. (Photo by Stephane Mahe/Reuters)

A man carries his dog as he prays during Vesak Day, an annual celebration of Buddha's birth, enlightenment and death, at Wat Yai Chai Mongkhon temple in Ayutthaya, Thailand, May 10, 2017. (Photo by Athit Perawongmetha/Reuters)

A Monster Jam truck performs a back flip during the first-ever monster truck event in Beijing's iconic “Bird's Nest” National Stadium on Saturday, July 29, 2017. (Photo by Ng Han Guan/AP Photo)

A participant dances as approximately 70,000 people from all over the world gathered for the annual Burning Man arts and music festival in the Black Rock Desert of Nevada, U.S. on August 29, 2017. (Photo by Jim Urquhart/Reuters)

Tactics reminiscent of the early American frontier days are now being used in Vietnam. Lieutenant Commander Donald D. Sheppard, UBN, of Coronado, California, aims a flaming arrow at a bamboo hut concealing a fortified Viet Cong bunker on the banks of the Bassac River, Vietnam on December 8, 1967. (Photo by AP Photo)