Japanese Ground Self-Defense Force's 1st Airborne Brigade soldiers board a CH-47 helicopter for parachute drop training during their military drill at Higashifuji training field in Susono, west of Tokyo, July 8, 2013. Japan faces increasingly serious threats to its security from an assertive China and an unpredictable North Korea, a defence ministry report said on Tuesday, as ruling politicians call for the military to beef up its ability to respond to such threats. (Photo by Issei Kato/Reuters)

A dog is kept at a pen at the newly opened Central Zoo in Pyongyang, North Korea, Tuesday, August 23, 2016. One of the most popular attractions at the zoo might come as a surprise to foreign visitors. Just across the way from the hippopotamus pen and the reptile house, dozens of varieties of dogs, including schnauzers, German shepherds, Shih Tzus and Saint Bernards – are on display in the “dog pavilion”. (Photo by Dita Alangkara/AP Photo)

South Korean Lee Jung-sook (L), 68, wipes the tears from her North Korean father Lee Heung-jong, 88, as they bid each other a sad farewell at a resort on Mount Kumgang, North Korea, 22 October 2015. About 390 South Koreans arrived at the resort two days ago for the first face-to-face reunion of families separated by the 1950-53 Korean War in nearly 20 months. A second group of some 260 South Koreans will do the same for three days starting on 24 October. (Photo by Yonhap/EPA)

Seiichiro Nishimoto, CEO of Shelter Co., poses wearing a gas mask at a model room for the company's nuclear shelters in the basement of his house in Osaka, Japan on April 26, 2017. With nearby North Korea increasing its show of power day by day with missile launches and nuclear tests, people in Japan are preparing for the worst by building private nuclear shelters, Reuters reports. (Photo by Kim Kyung-Hoon/Reuters)

Damir Sagolj has won Reuters photojournalist of the year for his 2016 work, which included documenting the deadly Philippine drug war and the North Korea congress. Here: A 17 year old girl lays dead next to her doll after she and her friend were killed by unknown motorcycle-riding gunmen, in an alley in Manila, Philippines early October 26, 2016. According to the police, a sign on a cardboard reading “Tulak ka, hayop ka”, which translates to “You are a (drug) pusher, you are an animal” was found with the body of girl's friend. (Photo by Damir Sagolj/Reuters)

A South Korean diver clad in Santa Claus costume swims with sardines at The Coex Aquarium on December 8, 2012 in Seoul, South Korea. Even though the official religion of South Korea is Buddhism, about 30 percent of it is Christian and Christmas is one of the biggest holidays to be celebrated in South Korea. (Photo by Chung Sung-Jun)

Sepak Takraw – ISTAF Super Series Korea 2014-15 – Gunsan City, South Korea April 26, 2015: Thailand's Fueangfa (L) in action during the final. (Photo by Jeremy Lee/Reuters)