Then U.S. Army First Lieutenant Kirsten Griest (C) and fellow soldiers participate in combatives training during the Ranger Course on Fort Benning, Georgia, in this handout photograph taken on April 20, 2015 and obtained on August 20, 2015. When Griest and another woman completed the daunting U.S. Army Ranger school this week they helped end questions about whether women can serve as combat leaders, as the Pentagon is poised to open new roles, including elite Navy SEALs, to women in coming months. The feat by Griest and First Lieutenant Shaye Haver followed a re-evaluation of the role of women after their frontline involvement in Iraq and Afghanistan and the end of a rule barring them from combat roles in 2013. (Photo by Spc. Nikayla Shodeen/Reuters/U.S. Army)

Mary McHugh mourns her slain fiance Sgt. James Regan at “Section 60” of the Arlington National Cemetery May 27, 2007. Regan, a US Army Ranger, was killed by an IED explosion in Iraq. (Photo by John Moore/Getty Images)

Police dog handlers wait outside the Loftus Road stadium after FA Cup Fourth Round between Queens Park Rangers and Chelsea on January 28, 2012 in London, England. Security has been stepped up after QPR player Anton Ferdinand recieved a package containing a bullet. (Photo by Dan Kitwood/Getty Images)

Sebastião Salgado is a Brazilian documentary photographer living in Paris. He has produced several books, and his work has been exhibited extensively around the world. His latest work, «Genesis», premieres at The Natural History Museum in London on April 11, on view through September 8, 2013. Photo: On South Georgia, a barren island in the far South Atlantic, a pair of southern elephant seal calves beckon before a colony of king penguins. “The male seals can grow to almost five tons,” says Salgado, “but these are just babies. This one looked at me with beautiful eyes”. (Photo by Sebastião Salgado/Amazonas/Contact Press Images)

Tasmanian devils play on May 31, 2023 in Sydney, Australia. Creatures living at the zoo welcomed the arrival of winter with snow and an array of treats. Many of the zoo's species would naturally experience seasonal changes within their wild ranges. With the support of the SEA LIFE Sydney Aquarium's sub-Antarctic penguin team, snow is predicted to hit the Darling Harbour-based attraction on Wednesday morning. (Photo by Jenny Evans/Getty Images)

In this photo taken Wednesday, October 29, 2014, a fisherman catches a fish near the shores of Lake Chivero, west of Harare. Illegal fishing can be hazardous in Zimbabwe, where poachers scan the banks for armed rangers and the water for crocodiles while they cast their rods. The country is in such a dire economic state that thousands of people, unable to find regular work, flock to Lake Chivero in hopes of catching fish, mostly bream, that they can sell for desperately needed income. (Photo by Tsvangirayi Mukwazhi/AP Photo)

Humboldt Penguins swim in their pool as a keeper looks on through a spherical window during the annual stocktake press preview at London Zoo in Regents Park in London Monday, January 4, 2016. A requirement of ZSL London Zoo's license, the annual audit takes keepers a week to complete and all of the information is shared with zoos around the world via the International Species Information System, where it's used to manage the worldwide breeding programmes for endangered animals. (Photo by Alastair Grant/AP Photo)

Members of the media film as a ranger performs a post mortem on the carcass of a rhino after it was killed for its horn by poachers at the Kruger national park in Mpumalanga province August 27, 2014. Rhino poachers in South Africa now risk giving themselves away when they shoot thanks to a high-tech, gunfire-detection system being piloted in the country's flagship Kruger National Park. The stakes are high, for rhinos are being slain in escalating numbers for their prized horns, alarming both conservationists and the government since wildlife in South Africa is an important tourist draw. (Photo by Siphiwe Sibeko/Reuters)