An Iranian student holds a cartoon by Mohammad Ali Khalaji during a demonstration against the Saudi-led coalitions operation against the Iran-backed Shiite rebels in Yemen on April 16, 2015 outside the United Nations (UN) offices in the capital Tehran. The UN envoy to Yemen has resigned after failing to avert large-scale violence, dealing a blow to hopes of a diplomatic solution to the conflict between rebels and Saudi-backed government forces. AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images)
