An environmental activist performs during a protest in front of the headquarters of Brazilian mining company Vale SA in downtown Rio de Janeiro, Brazil, November 16, 2015. The collapse of two dams at a Brazilian mine, owned by Vale SA and BHP Billiton Ltd, has cut off drinking water for quarter of a million people and saturated waterways downstream with dense orange sediment that could wreck the ecosystem for years to come. Nine people were killed, 19 are still listed as missing and 500 people were displaced from their homes when the dams burst at an iron ore mine in southeastern Brazil on November 5. (Photo by Sergio Moraes/Reuters)

A woman strikes a police truck with her hand during a protest march in Santiago, Chile, Thursday, April 16, 2015. Thousands of students marched through the streets of Chile's capital to protest recent corruption scandals and to complain about delays in a promised education overhaul. While it was largely peaceful, violence broke out at the end when hooded protesters threw rocks and gasoline bombs at police. (Photo by Luis Hidalgo/AP Photo)

Kenyan riot police officers raise batons over a man during a demonstration of Kenya's opposition supporters in Nairobi, on May 16, 2016. Opposition protestors led by former Prime Minister Raila Odinga gathered outside the Indepedent Electoral and Boundaries Comission building to demand the dismissal of IEBC commissioners, after alleged bias towards the ruling Jubillee Alliance Party. (Photo by Carl De Souza/AFP Photo)

Belgian riot police officers are covered by hay and eggs thrown by demonstrators as farmers and dairy farmers from all over Europe take part in a demonstration outside an European Union farm ministers emergency meeting at the EU Council headquarters in Brussels, Belgium, September 7, 2015. Thousands of farmers gathered in the European capital calling for more help with low prices and high costs. (Photo by Jacky Naegelen/Reuters)

Secondary school students perform a barefoot “pilgrimage of suffering” to support the Occupy Central civil disobedience movement at the Admiralty protest site in Hong Kong November 30, 2014. It has been two months since police first fired tear gas to disperse demonstrators from the main protest site in the Admiralty district next to government offices in the heart of the Asian financial centre. (Photo by Bobby Yip/Reuters)

An injured protestor is led away during clashes with police near Tahrir Square on November 23, 2011 in Cairo, Egypt. Thousands of Egyptians are continuing to occupy Tahrir Square after four days of clashes with security forces despite a promise from military leaders to bring forward Presidential elections. (Photo by Peter Macdiarmid/Getty Images)

Riot police hold their weapons during a protest by supporters of Kenyan opposition National Super Alliance (NASA) coalition, along a street in Nairobi, Kenya on October 11, 2017. Opposition leader Raila Odinga, has called for protests this week, reiterated that he would not take part in a re- run of the presidential election on October 26, 2017 if his demands are not met, as Kenya' s Supreme Court last month overturned the August election of President Uhuru Kenyatta citing “irregularities” in the counting of results. (Photo by Thomas Mukoya/Reuters)

British troops covered in flames from a petrol bomb thrown during a violent protest by job seekers, who say they were promised employment in the security services, in the southern Iraq city of Basra, March 22, 2004. (Photo by Atef Hassan/Reuters)