Children play in an outdoor shower as a soldier takes part in a surprise operation in the Manguinhos slum in Rio de Janeiro, Brazil, Thursday, January 18, 2018. Troops have been sent to Rio due to the increase of the violence, and in an attempt to help restore order, but so far have had little impact. The operation on Thursday took place three weeks ahead of Carnival, when thousands of tourists are expected to arrive in the city. (Photo by Leo Correa/AP Photo)

A cat wears a “Tsunagaru Col” gadget next to a smart phone displaying the connected app, at the Anicall Corp booth during the Wearable Device Technology Expo in Tokyo January 14, 2015. The gadget (“Tsunagaru” means connection) for animals tracks information about pets, such as the location and other animals the pet might be interacting with, with the purpose of providing “social networking” for animals. The expo runs until January 16 as a part of Japan's largest electronic exhibition expected to attract around 77,000 visitors, according to organisers. (Photo by Yuya Shino/Reuters)

A military police officer patrols in the Roquette Pinto shantytown, part of the Mare slum complex in Rio de Janeiro, Brazil, Wednesday, April 1, 2015. The Brazilian army has begun to pull out of one of Rio de Janeiro's most violent slums, with police assuming responsibility for security in the area. (Photo by Felipe Dana/AP Photo)

NATO and U.S. flags flutter as U.S. Air Force F-22 Raptor fighter flies over the military air base in Siauliai, Lithuania, April 27, 2016. (Photo by Ints Kalnins/Reuters)

Construction cranes stand on the Unstrut Valley high-speed railway bridge on March 19, 2012 near Karsdorf, Germany. The Unstrut bridge, which is 2,668m long (about 1.6 miles), is among 38 bridges and 26 tunnels German state rail carrier Deutsche Bahn is building along a new ICE high-speed railroad connection between Nuremberg, Erfurt, Halle, Leipzig and Berlin in a multi-billion Euro project across eastern Germany called the German Unity Transportation Project (Verkehrsprojekt der Deutschen Einheit). (Photo by Sean Gallup/Getty Images)

A French soldier stands near a military combat command vehicle on display at The Defence and Security Exhibition on September 13, 2011 in London, England. ExCeL London is hosting the exhibition with hundreds of manufacturers from all over the world displaying their hardware. (Photo by Peter Macdiarmid/Getty Images)

Omani Tactical & Commando personnel are seen during the month-long GCC joint security exercise “Arabian Gulf Security 1” in Manama, Bahrain November 1, 2016. “Arabian Gulf Security 1” exercises will continue until mid-November with the participation of the UAE, Saudi Arabia, Oman, Qatar and Kuwait. (Photo by Hamad I. Mohammed/Reuters)