Sudanese cattle keepers from Dinka tribe Makal Maker (R) and Achiek Butich pose with the guns for their protection at their cattle camp in Mingkaman, Lakes State, South Sudan, on March 2, 2018. (Photo by Stefanie Glinski/AFP Photo)

Law enforcement officers stand, with some turning their backs, as New York City Mayor Bill de Blasio speaks on a monitor outside the funeral for NYPD officer Wenjian Liu in the Brooklyn borough of New York January 4, 2015. Tens of thousands of law enforcement officers from across the country gathered on Sunday for the funeral of the second of two New York City policemen killed last month in an ambush that galvanized critics of Mayor de Blasio. (Photo by Shannon Stapleton/Reuters)

In this March 18, 2015 photo, Andrea, better known as Loira, which is the Portuguese word for “blonde”, poses for a portrait in an open-air crack cocaine market, known as a “cracolandia” or crackland where users can buy crack, and smoke it in plain sight, day or night, in Rio de Janeiro, Brazil. Andrea says she is married and has a home, but she keeps returning to crackland to feed her addiction. (Photo by Felipe Dana/AP Photo)

Tim Anderson final balanced rock stack in the Llano River. Tim Anderson, rock balancing “pro” from Pennsylvania, carefully worked to balance his stack on a dry spot in the Llano river Saturday March 12, 2016. He was an honored guest of the festival and enjoyed visiting Texas so he came for another year. The river was higher this year because of the rains so the balancers could not get to the better rock that were available last year. (Photo by Nell Carroll/American-Statesman)

Young Korean women wearing hanbok (Korean traditional dress) walk inside Gyeongbok Palace on March 27, 2016 in Seoul, South Korea. There has been a trend in recent years for the young Koreans to wear the traditional Korean dress, Hanbok. Wearing the traditional dress, they will walk around downtown Seoul on weekends taking selfies, and share their memories with friends on social media, and also to promote their traditional dress to foreign visitors. (Photo by Jean Chung/Getty Images)

The sun rises over St Mary's Lighthouse in Whitley Bay on the Northumberland coast as a flock of Lapwing seabirds fly past on Wednesday, September 30, 2015. (Photo by Owen Humphreys/PA Wire)

A woman walks on the stairs decorated with an image of two hands shaking to form the shape of the Korean Peninsula to support the upcoming inter- Korean summit, in downtown Seoul on September 17, 2018. South Korean President Moon Jae- in will fly to the North Korean capital on September 18, for his third summit with the North' s leader Kim Jong Un as a rapid diplomatic thaw takes hold on the peninsula despite stalled progress in denuclearisation talks between Pyongyang and Washington. (Photo by Jung Yeon-je/AFP Photo)

In this October 27, 1983 file photo, soldiers brandish captured AK-47 rifles from the windows of a civilian vehicle as they drive near Point Salines Airport in St. George, Grenada. In 1983, U.S. forces invaded the Caribbean island of Grenada after accusing the government of allying itself with Communist Cuba. (Photo by Doug Jennings/AP Photo)