A fireball erupts from a 16-inch gun on the battleship USS Wisconsin during a live fire exercise in the Persian Gulf, October 13, 1990. The ship is in the Gulf as part of Operation Desert Shield. (Photo by John Gaps III/AP Photo)

Armed Syrian Turkmen villagers are seen near the northern Syrian village of Yamadi, near the Turkish-Syrian border, Syria, November 24, 2015. Turkey shot down a Russian warplane near the Syrian border on Tuesday saying it had repeatedly violated its air space, one of the most serious publicly acknowledged clashes between a NATO member country and Russia for half a century. (Photo by Reuters/Stringer)

A man sleeps between tombstones in front of his single-room home on a hot night in the Cairo Necropolis, Egypt, October 13, 2015. In the sprawling Cairo Necropolis, known as the City of the Dead, life and death are side by side. Amid a housing crisis in Egypt, and with the population of greater Cairo estimated at about 20 million, people count themselves lucky to have a place to call home in the graveyards that date back hundreds of years. (Photo by Asmaa Waguih/Reuters)

In this December 13, 2014 photo, Ricardo Alegria holds his donkeys by a leash as he yells to sell their milk in the streets of Santiago, Chile. Alegria, along with his brother Marco, has been selling fresh donkey milk for the past 25 years, and says it's recommended as a vitamin boost. Shot glass size cups of the drink sell for about $2 dollars. Half a liter, which is the most he says his donkeys can give in one day, sells for about $20 dollars. (Photo by Luis Hidalgo/AP Photo)

A woman takes a picture of people posing in front of “Zinzow”, a “Transformers-inspired” sculpture constructed from scrap metal in Podgorica, July 22, 2014. Danilo Baletic, 22, makes sculptures of his childhood cartoon heroes, “Transformers”, from scrap metal. In the last two years he has made seven “Transformers” sculptures that are placed on the streets of Montenegro's capital Podgorica as part of an exhibition called “Transformers defending Podgorica”. (Photo by Stevo Vasiljevic/Reuters)

Man prepares wigs as he waits for customers in downtown Johannesburg, on August 5, 2014. Some estimates put Africa's dry hair industry at as much as $6 billion a year; Nigerian singer Muma Gee recently boasted that she spends 500,000 naira ($3,100) on a single hair piece made of 11 sets of human hair. (Photo by Siphiwe Sibeko/Reuters)

In this photo taken Wednesday, November 26, 2014 attack dogs and their handlers apprehend a “rhino poacher” center, after alighting from a helicopter into water, in a simulation exercise showing training at an academy run by the Paramount Group, near Rustenburg, South Africa. The course prepares canine units to find firearms or contraband, track suspects in the undergrowth and abseil in harnesses from helicopters in pursuit of poachers. Dogs and handlers learn to trust each other and fine tune a relationship balancing control and aggression. (Photo by Denis Farrell/AP Photo)

A visitor stands in front of a portrait taken by artist Bruce Gilden at the “Masters of Photography” exhibition at the Photokina trade fair in Cologne on September 20, 2016. The fair for the photographic and imaging sector, that is running from September 20 to 25, 2016, presents products from image capture, image processing and storage to image output. Photokina also includes a program of events with congresses, workshops, symposiums and photography exhibitions. (Photo by Patrik Stollarz/AFP Photo)