A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. At a rocky outpost in Western Sahara, a new generation of soldiers who have never known war are mobilising as tensions resurface in one of Africa's oldest disputes after a quarter century of uneasy peace. (Photo by Zohra Bensemra/Reuters)

An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

The Ivanpah Solar Electric Generating System is seen in an aerial view on February 20, 2014 in the Mojave Desert in California near Primm, Nevada. The largest solar thermal power-tower system in the world, owned by NRG Energy, Google and BrightSource Energy, opened last week in the Ivanpah Dry Lake and uses 347,000 computer-controlled mirrors to focus sunlight onto boilers on top of three 459-foot towers, where water is heated to produce steam to power turbines providing power to more than 140,000 California homes. (Photo by Ethan Miller/Getty Images)

A nurse helps an injured bomb victim sitting at the back of a pickup truck at the Asokoro General Hospital in Abuja, April 14, 2014. A morning rush-hour bomb killed at least 35 people at a Nigerian bus station near the capital on Monday, raising concerns about the spread of an Islamist insurgency after the first such attack on Abuja for two years. Suspicion fell on Boko Haram, though there was no immediate claim of responsibility from the Islamist group mainly active in the northeast. Five hours after the blast, officials had given no death toll. Reuters journalists counted at least 35 bodies. (Photo by Afolabi Sotunde/Reuters)

Undated UK Ministry of Defence handout photo of an RAF Tornado GR4 which has been painted in Gulf War “desert pink” paint scheme to honour the aircraft type's almost continuous operational service since the Royal Air Force helped liberate Kuwait from Saddam Hussein's forces, taken by SAC Rose Buchanan, which has been shortlisted for the general public to pick their favourite RAF Image of the Year. (Photo by SAC Rose Buchanan/MoD Crown Copyright/PA Wire)

A woman eats and struggles with her umbrella against powerful gusts of wind generated by typhoon Megi across the the island in Taipei, Taiwan, Tuesday, September 27, 2016. Schools and offices have been closed on Taiwan and people in dangerous areas have been evacuated as a large typhoon with 162 kilometers (100 miles) per-hour winds approaches the island. (Photo by Chiang Ying-ying/AP Photo)

An Indian paramilitary soldier stands guard at a polling station during the second phase of India's general elections, in Srinagar, Indian controlled Kashmir, Thursday, April 18, 2019. Kashmiri separatist leaders who challenge India's sovereignty over the disputed region have called for a boycott of the vote. Most polling stations in Srinagar and Budgam areas of Kashmir looked deserted in the morning with more armed police, paramilitary soldiers and election staff present than voters. (Photo by Dar Yasin/AP Photo)