Ma Jiaqi, 5, and her mother arrive at Beijing Railway Station for their train to Changchun of Jilin province, in Beijing, China, January 25, 2016. According to traffic police, over 2.9 billion trips will be made around China during the 40-day Spring Festival travel rush, which started on January 24. (Photo by Jason Lee/Reuters)

Vehicles clog a highway during a hazy day in Beijing, China, Wednesday, February 26, 2014. Beijing remained cloaked in hazardous white pollution hiding much of its skyline Wednesday, despite the announced closures or production cuts at 147 of the city's industrial plants. (Photo by Ng Han Guan/AP Photo)

A staff of the Beijing 2022 Winter Olympic Games holds a placard reading “Mask on” as USA's players react after their defeat in the women's gold medal match of the Beijing 2022 Winter Olympic Games ice hockey competition between Canada and USA, at the Wukesong Sports Centre in Beijing on February 17, 2022. (Photo by Kirill Kudryavtsev/AFP Photo)

Gunfire was brought to the steps of President Truman's Washington home, Blair House, as two assassins tried to kill the chief executive, November 1, 1950. One of the gunmen, Oscar Collazzo of New York, lay wounded at the bottom of Blair House's front steps after the president's police guard had finished their work, at the cost of one guards' life, Dec. 9, 1950. The second gunman was killed. (Photo by Harvey Georges/AP Photo)

(L-R) Senior Drum Major Betts of the Scotts Guard, Bugler Lee Kidd, Guardsman Adam Deer of the Coldstream Guards and Lance corporal Michael Strong of the Princess of Wales's Royal Regiment pose in their full ceremonial attire at Wellington Barracks on March 21, 2012 in London, England. The group make up part of the ceremonial military personnel who will play a key role during Her Majesty the Queens Diamond Jubilee celebrations between June 2–5. (Photo by Dan Kitwood/Getty Images)

Turkish guard police take special training, lasting 316 hours, for carrying out their job at best at Police Training Center Directorate of Guarding Training Academy of Turkiye on June 1, 2022. in Ankara, Turkiye. (Photo by Evrim Aydin/Anadolu Agency via Getty Images)

People take part in a military exercise for civilians conducted by veterans of the Ukrainian National Guard Azov battalion, amid threat of Russian invasion, in Kyiv, Ukraine on January 30, 2022. (Photo by Gleb Garanich/Reuters)

Timbuktu: A UN peacekeeper from Burkina Faso stands guard at the Djinguereber mosque, built in the 14th century, during a visit by a UN delegation on election day in Timbuktu, Mali, July 28, 2013. (Photo by Joe Penney/Reuters)