Soldiers stand guard in Maua square where a cotton candy vendor passes by in Rio de Janeiro, Brazil, Saturday, July 9, 2016, as security is deployed to get to know the areas they'll be patrolling during the Olympics. Roughly twice the security contingent at the London Olympics will be deployed during the August games in Rio, which are expected to draw thousands of foreigners to a city where armed muggings, stray bullets and turf wars between heavily armed drug gangs are routine. (Photo by Leo Correa/AP Photo)

Armed man stand at entrance of the naval headquarters in Sevastopol, March 19, 2014. Around a dozen Ukrainian servicemen, unarmed and in civilian clothes, walked out of the Ukrainian naval headquarters in the Crimean port of Sevastopol on Wednesday after it was taken over by pro-Russian forces, a Reuters witness said. (Photo by Baz Ratner/Reuters)

A Rajasthani folk dance artist performs while standing on two glasses during the “Dhora Ri Mahak” festival in Bhopal, India, 07 January 2015. The event is being organised by the “Indira Gandhi Rashtriya Manav Sangrahalaya” anthropology museum. (Photo by Sanjeev Gupta/EPA)

A muddied family photograph sits on a hallway stairwell in an apartment block on March 17, 2011 in Kensennuma, Japan. Residents were allowed back to their homes today and began the massive cleanup operation caused by a 9.0 magnitude strong earthquake that struck on March 11 off the coast of north-eastern Japan. The quake triggered a tsunami wave of up to 10 metres which engulfed large parts of north-eastern Japan. The death toll has risen past 5000 with at least 8600 people still missing. (Photo by Chris McGrath/Getty Images)

McMurdo Station is a U.S. Antarctic research centre located on the southern tip of Ross Island, which is in the New Zealand-claimed Ross Dependency on the shore of McMurdo Sound in Antarctica. It is operated by the United States through the United States Antarctic Program, a branch of the National Science Foundation. The station is the largest community in Antarctica, capable of supporting up to 1,258 residents, and serves as the United States Antarctic science facility. All personnel and cargo going to or coming from Amundsen–Scott South Pole Station first pass through McMurdo.

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

The 2016 Greenwich Village Halloween parade, October 31, 2016 in the Manhattan borough of New York City. (Photo by Anthony Causi)

In this Wednesday, January 7, 2015 photo, a Sri Lankan Catholic devotee Rita Anthony kisses her rosary as she prays inside her house in Colombo, Sri Lanka. The Vatican has said that it hopes that Sri Lanka's Christians can play a role in helping heal the wounds of the island nation's bloody 25-year civil war, when the Tamil Tiger rebels fought to create a separate homeland in the north for the minority Tamils, who are mostly Hindu. The war came to a bloody end in 2009, but many Tamils say they feel forgotten by the central government, which is dominated by the country's ethnic Sinhala majority, which is overwhelmingly Buddhist. Sri Lanka's Christians come from both the Tamil and the Sinhala communities, making them a natural bridge between the two sides. (Photo by Eranga Jayawardena/AP Photo)