Pakistani refugee children play in a slum on the outskirts of Tehran, capital of Iran, on June 20, 2018. June 20 is the World Refugee Day. (Xinhua/Ahmad Halabisaz)

Pakistani refugee children play in a slum on the outskirts of Tehran, capital of Iran, on June 20, 2018. June 20 is the World Refugee Day. (Xinhua/Ahmad Halabisaz)

Pakistani refugee children play in a slum on the outskirts of Tehran, capital of Iran, on June 20, 2018. June 20 is the World Refugee Day. (Xinhua/Ahmad Halabisaz)

Pakistani refugee children play in a slum on the outskirts of Tehran, capital of Iran, on June 20, 2018. June 20 is the World Refugee Day. (Xinhua/Ahmad Halabisaz)

The historic monument of Ghantaghar (the Clock Tower) is seen in Kathmandu, Nepal, June 20, 2018. As part of the World Refugee Day commemoration, the monument is illuminated in blue color for two days. June 20 is the World Refugee Day. (Xinhua/Sulav Shrestha)

Afghan refugee children pose for a photo at a slum in northwest Pakistan's Peshawar on June 20, 2018. June 20 is the World Refugee Day. (Xinhua/Saeed Ahmad)

Afghan refugees fill water bottles in eastern Pakistan's Lahore on June 20, 2018. June 20 is the World Refugee Day. (Xinhua/Jamil Ahmed)