A member of the United States Naval Academy freshman class crawls through trenches at the wet and sandy station during the annual Sea Trials training exercise at the U.S. Naval Academy on May 13, 2014 in Annapolis, Maryland. For 14 hours, the United States Naval Academy freshman class, also known as Plebes, worked as a team to complete many grueling physical and mental challenges that help prepare them for real-world experiences and reinforce leadership, bonds, trust, and teamwork. Of the challenges, they endured: a two-mile regimental run, ground fights, water tactics, aquatics challenges, and survival skills, amongst many others. (Photo by Patrick Smith/Getty Images)

A man carrying an axe walks past a house marked with bullet holes in Gyallesu district after recent clashes between Shi'ites and the army in Zaria, Kaduna state, Nigeria, February 3, 2016. Sectarian tensions are rising in Nigeria's Muslim north, where hundreds of Shi'ites were killed in clashes with the army in the town of Zaria in December, according to Shi'ites and rights groups. Following the clashes, bulldozers sent by the state levelled Shi'ite shrines, a cemetery and offices in the deeply divided town. The region is already grappling with an insurgency waged by the jihadist Boko Haram group. (Photo by Afolabi Sotunde/Reuters)

U.S. soldiers from 145th Field Artillery Battalion deployed from the United States fire Paladin self propelled gun during the Foal Eagle training exercise at firing point 180 at the Rodriguez Live Fire Range on March 15, 2012 in Pocheon, South Korea. (Photo by Chung Sung-Jun/Getty Images)

Goat herder Dana McGregor's goats Pismo, left, and Goatee surf at San Onofre State Beach, Calif, on July 11, 2012. McGregor started taking Pismo's mother Goatee to the beach, and it wasn't long before she was on a surfboard. When Pismo was born, McGregor put her on a board too, and she was a natural, he says. (Photo by Rod Veal/The Orange County Register via AP)

Sudanese refugees living in Tel Aviv dance as they celebrate independence from the Republic of Sudan on July 10, 2011 in Tel Aviv, Israel. Israel's Prime Minister Benjamin Netanyahu announced that Israel recognizes the Republic of South Sudan as independent state. South Sudan became a state on July 9 after it separated from the north, with its capital in Juba, following a vote for independence. The country was recognized on July 8 by the government of Sudan. (Photo by Uriel Sinai/Getty Images)

The hot air balloon “Hopper T Frog” from Park City, Utah, peeks over the red rock cliffs during the 23nd Annual Red Rock Balloon Rally at Red Rock State Park December 6, 2003 near Gallup, New Mexico. (Photo By Douglas Tesner/Getty Images)

People take pictures of the Tribute in Light while it is illuminated next to the Statue of Liberty (C), One World Trade Center and the Empire State Building during events marking the 14th anniversary of the 9/11 attacks on the World Trade Center in New York September 11, 2015. (Photo by Eduardo Munoz/Reuters)

A woman carries water during during a visit by a European Union delegation, at an IDP camp in Azaza, east of Ad Damazin, capital of Blue Nile state, October 21, 2015. The camp houses people displaced by war between the Sudan People's Liberation Movement-North (SPLM-N) rebels and the Sudanese government. (Photo by Mohamed Nureldin Abdallah/Reuters)