A U.S. Army crew chief flying on board a CH-47F Chinook helicopter observes the successful test of flares during a training flight in Afghanistan, March 14, 2018. (Photo by Tech. Sgt. Gregory Brook/Reuters/U.S. Air Force)

Iraqi government forces are seen near the Falahat village west of Fallujah on June 27, 2016. Iraqi forces took the Islamic State group's last positions in the city of Fallujah on June 26, establishing full control over one of the jihadists' most emblematic bastions after a month-long operation. (Photo by Moadh Al-Dulaimi/AFP Photo)

A hippopotamus performs during a show at the circus in Krasnoyarsk, Siberia, Russia, July 7, 2016. (Photo by Ilya Naymushin/Reuters)

Baby giraffe of Niger (Giraffa Camelopardalis) “Kenai” (R), born on August 25, 2016, kisses his mother “Dioni” on August 31, 2016 at the zoo of La Fleche, northwestern France. (Photo by Jean-Francois Monier/AFP Photo)

A bar girl shows off her sexual desires along the Walking Street where bars and sеx scenes are a commonplace July 31, 2016 in Pattaya, Thailand. Thailand's first female minister of tourism would like the sеx trade that is a huge business in the country to be banned. Tourists flock to Thailand for many sights including beautiful beaches but also for sеx tourism. Cities like Bangkok and Pattaya are well known as hubs of the Southeast Asian sеx trade, despite the fact that prostitution has been illegal in Thailand since 1960. (Photo by Paula Bronstein/Getty Images)

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

People dressed as a dancing devils with giant mask dance on a street, during a traditional celebration in Naiguata, Venezuela, Thursday, May 31, 2018. Carrying in their hands striking masks mostly animals and sea monsters, hundreds of men, women and children went out to dance frantically as possessed by evil spirits in an ancient ritual known as Dancing Devils of Naiguata, the unorthodox way of the coastal towns of Venezuela to venerate God during the celebrations of Corpus Christi. (Photo by Ariana Cubillos/AP Photo)

A horse is ridden out of the River Eden after being washed on the first day of the Appleby Horse Fair on June 7, 2018 in Appleby, England. The fair is an annual gathering for Gypsy, Romany and travelling communities. The event has existed under the protection of a charter granted by James II since 1685 and it remains one of the key meeting points for these communities. Around 10,000 travellers are expected to attend the event who traditionally come to buy and sell horses and it offers an opportunity for the traveller community to come together to celebrate their heritage and culture. (Photo by Ian Forsyth/Getty Images)