South Korean special warfare command soldiers participate in winter military training exercise on January 11, 2012 in Pyeongchang-gun, South Korea. The South Korean troops train in temperatures below -20 degrees celsius to defend the country against any possible attacks from North Korea. (Photo by Chung Sung-Jun/Getty Images)

Bottlenose dolphins leap off the Southern California coast on January 30, 2012 near Dana Point, California. A coalition that includes Native American tribes, Earthjustice and the Natural Resources Defense Council is on the National Marine Fisheries Service for more protection for dolphins, whales, and other migrating marine animals from the use of sonar in training by the US Navy on the West Coast. (Photo by David McNew/Getty Images)

A female Marine prepares to throw a practice grenade during Marine Combat Training (MCT) on February 21, 2013 at Camp Lejeune, North Carolina. Since 1988 all non-infantry enlisted male Marines have been required to complete 29 days of basic combat skills training at MCT after graduating from boot camp. MCT has been required for all enlisted female Marines since 1997. About six percent of enlisted Marines are female. (Photo by Scott Olson)

A performer poses with “The Gronkle” and “Deadly Nadder” at the How to Train Your Dragon Media Call at Fox Studios on November 29, 2011 in Sydney, Australia. The “How to Train Your Dragon Arena Spectacular” world premiere will take place in Australia in March 2012. (Photo by Brendon Thorne/Getty Images)

An animatronic dragon performs during the launch of How To Train Your Dragon Arena Spectacular at a Dreamworks and Global Creatures media call on August 8, 2011 in Melbourne, Australia. (Photo by Quinn Rooney/Getty Images)

A general view of atmosphere during the NYC “Soul Train” Line Flash Mob: Hippest Trip in America in honor of Don Cornelius in Times Square on February 4, 2012 in New York City. Cornelius, the creator of “Soul Train”, died on February 1, 2012 at the age of 75. (Photo by Ilya S. Savenok/Getty Images)

Gas-masked men of the British Machine Gun Corps with a Vickers machine gun during the first battle of the Somme, 1916. (Photo by General Photographic Agency/Getty Images)

Pfc. Sebastian Rodriguez, machine gunner, Weapons Platoon, Lima Company, 3rd Battalion, 3rd Marine Regiment, Marine Rotational Force – Darwin, fires an M240 machine gun during a night squad-attack exercise, here, May 22, 2013. (Photo by Sgt. Sarah Fiocco/U.S. Marines)