A demonstrator shows her arm with the name “Marielle” written on it, as she performs during a protest against the murder of councilwoman Marielle Franco in Rio de Janeiro, Brazil, Tuesday, March 20, 2018. Franco's murder came just a month after the government put the military in charge of security in Rio, which is experiencing a sharp spike in violence less than two years after hosting the 2016 Summer Olympics. (Photo by Leo Correa/AP Photo)

South Vietnamese forces escort suspected Viet Cong officer Nguyen Van Lem (also known as Bay Lop) on a Saigon street February 1, 1968, early in the Tet Offensive. Moments later, Lem was executed by Gen. Nguyen Ngoc Loan, chief of the national police. (Photo by Eddie Adams/AP Photo)

An ethnic Lisu man dances barefoot on hot charcoal embers to celebrate the annual Knife Pole Festival in Luzhang township of Nujiang Lisu Autonomous Prefecture in Yunnan province, China, March 29, 2018. (Photo by Aly Song/Reuters)

A truck transporting 20 tons of fish lost its load after crashing on a road near Liepen, eastern Germany on April 20, 2018. (Photo by Stefan Sauer/AFP Photo/DPA)

An Indian labourer carries a sack of plastic bottles on his head near one of the largest disposal sites in north-east India, ahead of the “World Environment Day” in Boragaon area of Guwahati on June 4, 2018. World Environment Day is marked annually on June 5, and aims at promoting awareness and action to protect the environment. (Photo by Biju Boro/AFP Photo)

In this Thursday, July 19, 2018, photo, a Syrian shopkeeper spraying water as waits for customers at the Hamadiyah market, named after the 34th Sultan of the Ottoman Empire Abdul Hamid II, in the Old City of Damascus, Syria. The celebratory mood in government-controlled areas stems from successive military advances in the past year and an impression that President Bashar Assad, with massive support by unwavering allies Russia and Iran, has won the war or at least militarily defeated the opposition trying to topple him. (Photo by Hassan Ammar/AP Photo)

A man rides a horse while others swim on the beach of Gaza City, Friday, August 3, 2018. (Photo by Khalil Hamra/AP Photo)

A fisherman throws a net for catching fish with his wife in Yanhu fisherman village near Yangzhou, Jiangsu province, China, 18 October 2018. (Photo by Aleksandar Plavevski/EPA/EFE)