Soldiers take part in a drill during a heavy snow in Heihe, Heilongjiang province, February 26, 2014. (Photo by Reuters/China Daily)

Over 30 Douglas C-47 Skytrains (Dakotas) making final preparations for flight formation practice before the 75th D-Day Anniversary flight to Normandy in Duxford, England on June 4, 2019. (Photo by UK Air Force Images)

Female North Korean soldiers parade to mark the 60th anniversary of the signing of a truce in the 1950-1953 Korean War at Kim Il-sung Square, in Pyongyang. (Photo by Jason Lee/Reuters)

Bonobo apes, primates unique to Congo and humankind's closest relative, groom one another at a sanctuary just outside the capital Kinshasa, Congo on October 31, 2006. (Photo by Finbarr O'Reilly/Reuters)

In this April 20, 2017 photo, a woman is aided by fellow demonstrators after falling, overcome by tear gas, during anti-government protests in Caracas, Venezuela. Tens of thousands of protesters asking for the resignation of President Nicolas Maduro flooded the streets again, one day after three people were killed and hundreds arrested in the biggest anti-government demonstrations in years. (Photo by Ariana Cubillos/AP Photo)

An AH-64D Apache attack helicopter flies in front of a wall of fire during the South Carolina National Guard Air and Ground Expo at McEntire Joint National Guard Base, South Carolina, U.S. on May 6, 2017. (Photo by Jorge Intriago/Reuters/Courtesy Air National Guard)

A dirty thunderstorm occurs over Mount Sakurajima as the volcano erupts violently at 12:03 am on July 26, 2016 in Tarumizu, Kagoshima, Japan. The eruption occurred at the mountain's Showa crater. This is the first time that the active volcano in southern Kyushu has spewed out a smokestack that high since an eruption on August 18, 2013, according to the Kagoshima Meteorological Office. (Photo by The Asahi Shimbun via Getty Images)