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)

A cat walks in front of the body of a man killed by unknown gunmen in Manila, Philippines early October 18, 2016. A sign on a cardboard found near the body reads, “Pusher Ako, Wag Tularan”, which translates to “I am a (drug) pusher, don't be like me”. (Photo by Damir Sagolj/Reuters)

A boy holds the remains of a mortar shell which hit a residential building in the village of Staromikhailovka, outside the separatist-held city of Donetsk, Ukraine, May 24, 2016. (Photo by Alexander Ermochenko/Reuters)

In this March 7, 1991 file photo, a U.S. Marine patrol walks across the charred oil landscape near a burning well during perimeter security patrol near Kuwait City. Twenty five years after the first U.S. Marines swept across the border into Kuwait in the 1991 Gulf War, American forces find themselves battling the extremist Islamic State group, born out of al-Qaida, in the splintered territories of Iraq and Syria. The Arab allies that joined the 1991 coalition are fighting their own conflicts both at home and abroad, as Iran vies for greater regional power following a nuclear deal with world powers. (Photo by John Gaps III/AP Photo)

Brush fires in Everglades National Park, Florida make for a dramatic Milky Way in this panorama. A photographer set out to inspire awe in nature's wonders through the tropical wetlands of Florida. (Photo by Mark Andrew Thomas/Rex Feature/Shutterstock)

Actress Scarlett Johansson Honored With The Star On The Hollywood Walk Of Fame on May 2, 2012 in Hollywood, California. (Photo by Jon Kopaloff/FilmMagic)

A portrait of French WWI soldier Edouard Marius Ivaldi is displayed on a tablet, in this illustration picture, alongside his battlefield grave memorial, a wooden cross with a battlefield helmet in Champagne, eastern France, November 3, 2015. (Photo by Charles Platiau/Reuters)