Masked Palestinian demonstrators hide behind a metal plate during clashes with Israeli soldiers on March 12, 2018 in the West Bank town of Birzeit, near Ramallah, following a protest by students of the Birzeit University against the arrest of the the head of Palestinian student council by an Israeli undercover commando. (Photo by Abbas Momani/AFP Photo)

A Broto dancer prepares himself in a disused house of Bambari, in the centre of Central African Republic, before performing on March 14, 2019. The Broto, belonging to the Banda ethnic group, are known for their traditional dances accompanied by heavy horns made of tree roots. Today this tradition falls into disuse and its history is now forgotten by the new generations. (Photo by Florent Vergnes/AFP Photo)

Rwandan refugees cross the Rusumo border to Tanzania from Rwanda carrying their belongings, goats, mattresses and cows, May 30, 1994. The bloodshed that claimed 800,000 Tutsi and moderate Hutu lives began 25 years ago on April 7, 1994, when a plane carrying Rwandan President Juvenal Habyarimana, Burundi President Cyprien Ntaryamira and a French air crew was shot down. (Photo by Jeremiah Kamau/Reuters)

Waura Indians wrestle during this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, Brazil August 25, 2013. (Photo by Ueslei Marcelino/Reuters)

An army tank fires during a firefight against militants linked to al Qaeda near the southern Yemeni city of Zinjibar May 30, 2012. (Photo by Reuters/Yemen's Defence Ministry)

People immerse themselves in an ice hole in the Chulym river, with the air temperature at about minus 12 degrees Celsius (10.4 degrees Fahrenheit), during celebrations for the Russian Orthodox Epiphany outside of the town of Nazarovo, Krasnoyarsk region January 19, 2015. (Photo by Ilya Naymushin/Reuters)

An Afghan National Army (ANA) soldier assigned to the Mobile Strike Force Kandak fires a RPG-7 rocket-propelled grenade launcher during a live-fire exercise supervised by the Marines with the Mobile Strike Force Advisor Team on Camp Shorabak, Helmand province, Afghanistan, May 20, 2013. The Marines with the Mobile Strike Force Advisor Team instructed and mentored their ANA counterparts on how to properly utilize their weapons systems. (Photo by SSgt Ezekiel R. Kitandwe/RCT 7)

A photo taken on August 29, 2014, shows Mount Tavurvur erupting in eastern Papua New Guinea, spewing rocks and ash into the air, forcing the evacuation of local communities and international flights to be re-routed. Mount Tavurvur, which destroyed the town of Rabaul when it erupted simultaneously with nearby Mount Vulcan in 1994, rumbled to life early in the morning on the tip of the remote island of New Britain. (Photo by Oliver Bluett/AFP Photo)