Members of the U.S. Army 173rd Airborne Brigade stand at attention as a Ukrainian folk dance group performs at the opening ceremony of the “Rapid Trident” NATO military exercises on September 15, 2014 near Yavorov, Ukraine. The two-week exercises include participating units from a variety of NATO and NATO-associate countries as well as Ukrainian troops. Meanwhile fighting between pro-Russian separatists and Ukrainian armed foces has flared again in eastern Ukraine in a battle for the control of Donetsk airport despite the tenuous ceasefire. (Photo by Sean Gallup/Getty Images)

The moon illuminates the snow-covered Concordia, the confluence of the Baltoro and Godwin-Austen glaciers, near the world's second highest mountain the K2 (8,000 meters) in the Karakoram mountain range in Pakistan September 6, 2014. While other parts of Pakistan and northern India were flooded, Concordia in the Karakoram mountain range was covered with a seasonally unusual amount of snow. Geographically, Pakistan is a climbers paradise. It rivals Nepal for the number of peaks over 7,000 meters and is home to the world's second tallest mountain, K2, as well as four of the world's 14 summits higher than 8,000 meters. (Photo by Wolfgang Rattay/Reuters)

A man helps another make his way through deep mud at the site of a landslide at the Koslanda tea plantation near Haldummulla October 30, 2014. Hopes of finding survivors under the mud and rubble of a landslide in south-central Sri Lanka had run out by first light on Thursday, though a government minister cut the estimated death toll to more than 100 from 300 the previous night. (Photo by Dinuka Liyanawatte/Reuters)

Russia-backed separatists stand at the site of the crashed Malaysia Airlines Flight 17 plane, near the village of Hrabove, eastern Ukraine, Thursday, July 16, 2015. The fighters said they have arrived to protect the media and make sure the MH17 crash site is clear of ammunition and mines. A year since a Malaysia Airlines Boeing 777 was blown out of the sky over war-ravaged eastern Ukraine, killing 298 people, there has been little official word of progress in determining what brought down Flight MH17. (Photo by Antoine E. R. Delaunay/AP Photo)

An employee holds a plant with roots at the Plant Advanced Technologies (PAT) company greenhouse in Laronxe near Nancy, Eastern France, June 19, 2015. The farmers employed at the site in Laronxe are growing plants in a special way with a view to “milking” them for use in medicines, cosmetics and agrochemicals. Several major brands, including Germany's BASF and France's Chanel, have teamed up with Plant Advanced Technologies (PAT) in the hope of securing privileged access to the so-called “biomolecules” it extracts through the use of a patented technique. (Photo by Vincent Kessler/Reuters)

A sinkhole is seen on the shore of the Dead Sea near Kibbutz Ein Gedi, Israel July 27, 2015. The Dead Sea is shrinking, and as its waters vanish at a rate of more than one meter a year, hundreds of sinkholes, some the size of a basketball court, some two storeys deep, are devouring land where the shoreline once stood. (Photo by Amir Cohen/Reuters)

Actors reenact the famous picture of a sailor kissing a nurse on the 70th anniversary of Victory over Japan Day, near a replica sculpture in New York's Times Square August 14, 2015. The replica is being displayed to celebrate the 70th anniversary of the iconic photograph of the most famous kiss in American history that was captured between an American sailor and nurse on August 14, 1945, marking the end of World War Two. The actors are hired by a tour bus company to pose for groups to photograph. (Photo by Brendan McDermid/Reuters)

A Japanese Ground Self-Defense Force Type 92 Mine sweeping vehicle fires a rocket behind a Type 74 armoured tank during an annual training session, which is based on a scenario to defend or retake islands in Japanese territory, near Mount Fuji at Higashifuji training field in Gotemba, west of Tokyo, August 18, 2015. (Photo by Yuya Shino/Reuters)