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)

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

Alexandra Mazo, 12, with her cellphone on her way down the mountain after finishing school. The remote mountain village of Pueblo Nuevo has been highly affected by the armed conflict and direct combat between the national army and Farc guerrillas due to its strategic location and the intensive production on coca crops on the surrounding hillsides. (Photo by Mads Nissen/Politiken/The Guardian/Panos Pictures/The Nobel Peace Center)

In this Friday, August 9, 2019, file photo, Pakistan Rangers soldiers face Indian Border Security Force soldiers at a daily closing ceremony on the Indian side of the Attari-Wagah border. India's recent clampdown has a long history in Kashmir and the conflict has existed since the late 1940s, when India and Pakistan won independence from the British empire and began fighting over rival claims to the Muslim-majority territory. India and Pakistan have fought two of their three subsequent wars over Kashmir, and each administers a portion of the region. India has long seen the Kashmiri struggle for self-determination as Islamabad's proxy war against New Delhi. (Photo by Prabhjot Gill/AP Photo/File)

Ballerina Kira Hilli of the Netherlands National Ballet dances in a tutu with a diameter of 3 meters for a video made for the 1.5 meter society, on the Prinsengracht in Amsterdam, The Netherlands, 04 June 2020 (issued on 12 June 2020). The so-called social distance tutu is made of denim fabric, specially made for the Safe Distance Ballet. (Photo by Remko de Waal/EPA/EFE)

Indonesian firefighters spray disinfectant at the public area near an elephant enclosure at Ragunan Zoo prior to its reopening this weekend after weeks of closure due to the large-scale restrictions imposed to help curb the new coronavirus outbreak, in Jakarta, Indonesia, Wednesday, June 17, 2020. As Indonesia's overall virus caseload continues to rise, the capital city has moved to restore normalcy by lifting some restrictions, saying that the spread of the virus in the city of 11 million has slowed after peaking in mid-April. (Photo by Dita Alangkara/AP Photo)

A fisherman waits to catch fish as he sits atop a stilt in the sea in Koggala, Sri Lanka on July 4, 2019. (Photo by Dinuka Liyanawatte/Reuters)