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)

People pass by a vehicle almost completely submerged on a street covered with mud due to heavy floods in Tekija village September 17, 2014. One person died in Serbia and authorities scrambled to evacuate hundreds of people from villages threatened by rising rivers, officials said on Tuesday, in scenes recalling the devastating May flooding that killed dozens. (Photo by Djordje Kojadinovic/Reuters)

A gannet grabs a fish by its beak, 2014, in Shetland, Scotland. Hundreds of gannets crash into the sea in search of food – leaving a trail of air bubbles in their wake. Richard Shucksmith, 41, on the Shetland Isles, Scotland captured the remarkable scene as he took a boat to feed the large colony of seabirds that nested on the cliffs. The photographer has taken images of the gannets every summer for the last three years as the birds gather on the cliffs to breed. (Photo by Richard Shucksmith/Barcroft media)

Britain's BASE jumper Sam Hardy lives up to his name after throwing himself off the top of the 335m-high Kuala Lumpur Tower during the KL Tower International Jump in Kuala Lumpur, Malaysia, Saturday, September 27, 2014. BASE stands for the places such jumpers usually jump from: buildings, antennas, spans (bridges) and earth (cliffs). (Photo by Lai Seng Sin/AP Photo)

Harry Potter collectible busts are displayed in the home of Menahem Asher Silva Vargas, after he was presented with a Guinness World Record title certificate for the largest collection of Harry Potter memorabilia, in Mexico City, Monday, September 29, 2014. Silva's collection consists of more than 3000 individual items, including trading cards, wands, and books in multiple languages. (Photo by Rebecca Blackwell/AP Photo)

A pro-Russian supporter with the Russian national flag on her shoulders takes part in a meeting in Simferopol, March 6, 2014. Crimea's parliament voted to join Russia on Thursday and its Moscow-backed government set a referendum within 10 days on the decision in a dramatic escalation of the crisis over the Ukrainian Black Sea peninsula. (Photo by Vasily Fedosenko/Reuters)

A Palestinian youth jumps with a sword as he demonstrates his ninja-style skills for the photographer in front of the ruins of buildings, that were destroyed in 2014 war, in the northern Gaza Strip January 29, 2016. The youths, who have been receiving martial arts training at local clubs in Gaza for the past two years, decided to form a team to hold regular shows in the hope that the publicity generated will eventually lead to them being invited to participate in international contests. (Photo by Mohammed Salem/Reuters)

In this August 1, 2014 photo provided by the National Park Service are male caribou antlers in the Oolah Valley, likely the result of a grizzly kill as he migrated south for the winter at the Arctic National Park and Preserve in Alaska. The nation's northernmost national park says its new management plan will have to consider the effects of a new industrial road to the mining district of Ambler, the first road that would be constructed within its Maryland-sized boundaries. (Photo by Cadence Cook/AP Photo/National Park Service)