Since the operation to liberate Fallujah began, the U.N. says they have received reports that some 500 men and boys have been detained for questioning as thousands of civilians have fled the city's mostly rural outskirts.
Joseph Kabila (right), President of the Democratic Republic of the Congo, during the fourth meeting of the regional oversight mechanism of the Peace, Security and Cooperation Framework for the Democratic Republic of the Congo and the Region on Sept. 22, 2014 at the United Nations in New York City. (UN Photo/Amanda Voisard)
Jimmy Morales, president of the Republic of Guatemala, addresses the United Nations' special session on global drug policy at U.N. headquarters on April 19, 2016. It is the first U.N. special session to address global drug policy in nearly 20 years. (Associated Press)
National Edition News cover for July 23, 2015 - Obama aides deny secret U.N. side deals with Iran: Members of the Security Council vote at United Nations headquarters, Monday, July 20, 2015. The U.N. Security Council unanimously endorsed the landmark nuclear deal between Iran and six world powers and adopted a series of measures leading to the end of U.N. sanctions that have hurt the Iranian economy. (AP Photo/Seth Wenig)
Members of the Security Council vote at United Nations headquarters, Monday, July 20, 2015. The U.N. Security Council unanimously endorsed the landmark nuclear deal between Iran and six world powers and adopted a series of measures leading to the end of U.N. sanctions that have hurt the Iranian economy. (AP Photo/Seth Wenig)
Syria overtook Afghanistan to become the world's biggest source of refugees last year, while the number of people forced from their homes by conflicts worldwide rose to a record 59.5 million, the United Nations' refugee agency said Thursday, June 18, 2015. (AP Photo/Petros Giannakouris, File)
UN Secretary General Ban Ki-moon arrives on the eve of the Geneva Consultations on Yemen at the European headquarters of the United Nations, UN, in Geneva, Switzerland, Sunday, June 14, 2015. (Laurent Gillieron/Keystone via AP)
FILE - In this Friday, March 20, 2015 file photo, U.N. special envoy to Libya, Bernardino Leon, speaks during a press conference at the Palais des Congres of Skhirate, 30 kilometers (19 miles) south of Rabat, Morocco. Libya's parliament drops out of U.N.-brokered negotiations in protest against a draft plan for it to share power with its rivals, throwing doubt on what is seen as a last-chance effort to avert the further collapse of the North African nation. (AP Photo/Abdeljalil Bounhar, File)