Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

A couple takes a selfie as Hoa Binh hydroelectric power plant opens the flood gates after a heavy rainfall caused by Talas typhoon in Hoa Binh province, outside Hanoi, Vietnam July 20, 2017. (Photo by Reuters/Kham)

A handout TV grab made available by the Demiroren News Agency (DHA) on September 12, 2020, shows a freak sandstorm sweeping over Polatli, in Ankara, on September 12, 2020. A freak sandstorm hit Ankara on September 12, 2020, the Turkish capital's mayor said, as officials said six people were injured after strong winds. (Photo by Handout/DHA via AFP Photo)

A man stands next to a horsecart laden with oil drums on a street in Lahore on September 27, 2020. (Photo by Arif Ali/AFP Photo)

In this photograph taken on February 15, 2021, doctor Sergen Saracoglu (L) and nurse Yilzdiz Ayten (C) from the Bahcesaray public hospital vaccination team, arrive at the village of Guneyyamac in eastern Turkey, as part of an expedition to vaccinate residents of 65 years old or above with Sinovac's CoronaVac Covid-19 vaccine. (Photo by Bulent Kilic/AFP Photo)

Female Siberian tiger Dasha yawns in the new enclosure at the zoo in Duisburg, Germany, 30 March 2016. The new facility is three times larger than the old one and will be opened to the public on the same day. (Photo by Roland Weihrauch/EPA)

A great tit eats food from the top of a photographer's hat as the press wait for politicians on Downing Street on December 16, 2019 in London, England. The UK's Prime Minister is set to hold a mini Cabinet reshuffle to replace outgoing ministers following last week's general election victory. (Photo by Leon Neal/Getty Images)

Ammunition airlift into besieged Khe Sanh, Operation Pegasus, April 1968. (Photo by Larry Burrows/AP Photo)