FILE - In this Feb. 12, 1979 file photo, armed rebels, one wearing a gas mask, ride in a truck near the headquarters of Ayatollah Khomeini, in Tehran, Iran. Monday, Feb. 11, 2019 marks the 40th anniversary of the Islamic Revolution. On Feb. 11, 1979, after days of running street battles and uncertainty, Iran‚Äôs military stood down and allowed the Islamic Revolution to sweep across the country. The caretaker government left behind by the cancer-stricken Shah Mohammad Reza Pahlavi, who weeks earlier left the nation, quickly crumbled as the soldiers once backing it embraced the supporters of Ayatollah Ruhollah Khomeini. (AP Photo/Campion, File)