Officers react at their graduation ceremony during Iraqi Army Day anniversary celebration in Baghdad January 6, 2015. Iraqi Defence Minister Khaled al-Obeidi said on Tuesday that the Iraqi military has started rebuilding after its near total collapse last summer but that the effort is still in its initial phase. (Photo by Ahmad Mousa/Reuters)

On September 1, 2004, Chechen militants stormed an elementary school in the town of Beslan in the Russian republic of North Ossetia. They took 1,100 teachers, children, and their relatives hostage, demanding the withdrawal of federal forces from Chechnya as a condition for their release. On September 3, 2004, Russian security forces stormed the building, resulting in a battle in which more than 330 hostages died, including 186 children. Here: A man assists two young hostages who managed to escape from the school building after special forces entered the school in Beslan, North Ossetia, Friday 03 September 2004. (Photo by Yuri Kochetkov/EPA)

A clown poses for a picture in a parade during Salvadoran Clown Day celebrations in San Salvador, El Salvador, December 7, 2016. (Photo by Jose Cabezas/Reuters)

Fr. Denis Crosby blesses a live lamb during a Pattern Day mass to St. Brigid at the holy well of St. Brigid in Liscannor, Ireland February 1, 2017. (Photo by Clodagh Kilcoyne/Reuters)

A dancer prays before she performs as land activists gather to commemorate the upcoming Women's Day in Phnom Penh, Cambodia, March 7, 2017. (Photo by Samrang Pring/Reuters)

Race goers are pictured during the Investec Ladies Day at Epsom Downs Racecourse on June 2, 2017 in Epsom, England. (Photo by News Group Newspapers Ltd)

This photo taken on June 19, 2017 shows Indian yoga teacher Mahesh Yogiji attempting a world record for the longest yoga session in Ahmedabad, ahead of International Yoga Day on June 21. According to Guiness World Records, the longest yoga marathon undertaken by a man lasted 69 hours and was achieved by V Gunasekaran in Tamil Nadu in June 2016. (Photo by Sam Panthaky/AFP Photo)

A girl collects drinking water at Dala river outside Yangon, Myanmar March 3, 2016. Some 650 million people, or one in 10 of the world's population, have no access to safe water, putting them at risk of infectious diseases and premature death. Dirty water and poor sanitation can cause severe diarrhoeal diseases in children, killing 900 under-five a day across the world, according to United Nations estimates. (Photo by Soe Zeya Tun/Reuters)