Mary McHugh mourns her slain fiance Sgt. James Regan at “Section 60” of the Arlington National Cemetery May 27, 2007. Regan, a US Army Ranger, was killed by an IED explosion in Iraq. (Photo by John Moore/Getty Images)

A competitor looses control of his pancake while racing during the Shrove Tuesday, or Mardi Gras, tradition at the National Cathedral February 21, 2012 in Washington, DC. (Photo by Chip Somodevilla/Getty Images)

A woman reacts as she receives the AstraZeneca/Oxford vaccine under the COVAX scheme against coronavirus disease (COVID-19) at the Kenyatta National Hospital in Nairobi, Kenya on March 5, 2021. (Photo by Monicah Mwangi/Reuters)

A model composes herself during the Ukrainian Fashion Week 2020-2021 at the Mystetskyi Arsenal National Art and Culture Museum Complex on February 4, 2020. (Photo by Irynka Hromotska/Radio Free Europe/Radio Liberty)

A National Guard member mounts guard as a man exercises during a rally against George Floyd death in Minneapolis police custody, in Los Angeles, California, U.S., June 2, 2020. (Photo by Mike Blake/Reuters)

Giraffes cross under the bridge of the Standard Gauge Railway (SGR) line inside the Nairobi National Park in Nairobi, Kenya, May 25, 2020. (Photo by Baz Ratner/Reuters)

A plane battling the Ferguson Fire passes the setting sun in unincorporated Mariposa County Calif., near Yosemite National Park on Sunday, July 15, 2018. (Photo by Noah Berger/AP Photo)

Climbers place a huge 80x80 metres (262x262 feet) Swiss national flag on the western face of the north-eastern Swiss landmark Mount Saentis, Switzerland on July 31, 2018. (Photo by Arnd Wiegmann/Reuters)