Members of the Bavarian police and the Bundeswehr, the German armed forces, guard a vehicle checkpoint as they demonstrate a dynamic operation as part of the GETEX anti-terror exercises during a media event on March 9, 2017 in Murnau, Germany. (Photo by Philipp Guelland/Getty Images)

A demonstrator catches fire after the gas tank of a police motorbike exploded during clashes in a protest against Venezuelan President Nicolas Maduro, in Caracas on May 3, 2017. Venezuela' s angry opposition rallied Wednesday vowing huge street protests against President Nicolas Maduro' s plan to rewrite the constitution and accusing him of dodging elections to cling to power despite deadly unrest. (Photo by Juan Barreto/AFP Photo)

Police detain a protester during a demonstration against the recent gang-rape of a woman in a moving car, according to local media, in Kolkata, India May 31, 2016. A woman was kidnapped and gang-raped by at least four men on May 29 in the Salt Lake area of the city and is currently being treated in hopsital, local media reported. (Photo by Rupak De Chowdhuri/Reuters)

A riot police blocks a street during a march near a meeting attended by the Secretary-General of Organization of American State Luis Almagro and leaders from various communities in Managua, Nicaragua, December 1, 2016. (Photo by Oswaldo Rivas/Reuters)

In this file photo taken on Saturday May 1, 1993, an elderly communist woman clutches her head as police on horseback patrol the streets in Moscow. When Alexander Zemlianichenko started working as an AP photographer in Moscow, the Soviet Union was nearing its demise. (Photo by Alexander Zemlianichenko/AP Photo)

In this Monday, July 24, 2017 photo, a police officer walks in front of a mural during a protest demanding an end to the current pension fund system, in Santiago, Chile. Protesters say the government pension system robs retirees of fair pension payments, and are demanding a new social security system with higher payments. (Photo by Esteban Felix/AP Photo)

Indian policemen carry the body of one of their colleagues killed in a rebel attack in the town of Dinanagar, in the northern state of Punjab, India, Monday, July 27, 2015. Indian forces fought an extended gunbattle Monday with militants who attacked a moving bus and stormed into a police station in a northern town bordering Pakistan. (Photo by Channi Anand/AP Photo)

A protester holding a torch runs past police (not pictured) trying to stop the protesters from marching in a rally organised by a 30-party alliance led by a hardline faction of former Maoist rebels, who are protesting against the draft of the new constitution, in Kathmandu August 15, 2015. The group says that the draft is not inclusive and does not protect the rights of the marginalised and underprivileged groups in the country. (Photo by Navesh Chitrakar/Reuters)