A US Army M1A2 SEP tank participates in the Strong Europe Tank Challenge 2017 at the military training area in Grafenwoehr, Germany, 12 May 2017. Six North Atlantic Treaty Organization (NATO) nations and partner nations, Austria, France, Germany, Poland, Ukraine and the USA are taking part in this competing exercise. (Photo by Christian Bruna/EPA)

Russian Police academy female cadets march during a rehearsal for the Victory Day military parade at Dvortsovaya (Palace) Square in St Petersburg, Russia, Wednesday, May 7, 2014. Victory Day, marking the defeat of Nazi Germany, is Russia's most important secular holiday celebrated on May 9. (Photo by Dmitry Lovetsky/AP Photo)

Chinese women wear protective masks as they are dressed in traditional clothing from the Qing Dynasty era outside a park on March 29, 2020 in Beijing, China. A limited section of the iconic tourist site was re-opened to the public this week allowing a smaller number of visitors to reserve tickets online in advance and to enter after passing health screening. (Photo by Kevin Frayer/Getty Images)

A demonstrator throw a firebomb during clashes with Turkish riot police officers in Istanbul, Turkey, Friday, May 1, 2015. The government assigned 30,000 police officers backed by helicopters as workers and demonstrators determined to defy a government ban, tried to march to iconic Taksim Square, where 35 people were killed during May Day celebration in 1977. (Photo by Emrah Gurel/AP Photo)

Female North Korean traffic police officers gather in front of bronze statues of the late leaders Kim Il Sung and Kim Jong Il to pay their respects in Pyongyang, North Korea on Saturday, February 16, 2013. North Koreans turned out to commemorate what would have been the 71th birthday of Kim Jong Il who died on December 17, 2011. (Photo by David Guttenfelder/AP Photo)

A Pakistani scavenger girl writes on a notebook she collected from a garbage, while another girl sits next to her in Lahore, Pakistan, Wednesday, April 1, 2015. Thousands of children pick recyclable items from waste dumping points to earn living for their poor families. (Photo by K. M. Chaudary/AP Photo)

A competitor reacts as she emerges from the water during the Tough Guy event in Perton, central England, January 26, 2014. The annual Tough Guy race – “the toughest race in the world” – at Perton in Staffordshire. Tough Guy claims to be the world’s most demanding one-day survival ordeal. First staged in 1987, the Tough Guy Challenge has been widely described as one of the hardest races of it’s type with up to one-third of the starters failing to finish in a typical year. (Photo by Darren Staples/Reuters)

A migrant worker wearing face masks to help curb the spread of the coronavirus walks up to a pedestrian bridge in Beijing, Sunday, December 6, 2020. Provincial governments across China are placing orders for experimental, domestically made coronavirus vaccines, though health officials have yet to say how well they work or how they may reach the country's 1.4 billion people. (Photo by Andy Wong/AP Photo)