FILE - In this Sept. 22, 2014 file photo, members of the Iran's Revolutionary Guard march during an annual military parade at the mausoleum of Ayatollah Khomeini, outside Tehran, Iran. On Monday, April 8, 2019, the Trump administration designated Iran’s Revolutionary Guard a “foreign terrorist organization” in an unprecedented move against a national armed force. Iran’s Revolutionary Guard Corps went from being a domestic security force with origins in the 1979 Islamic Revolution to a transnational fighting force. (AP Photo/Ebrahim Noroozi, File)
In this Sept. 22, 2014 file photo, members of the Iran's Revolutionary Guard march during an annual military parade at the mausoleum of Ayatollah Khomeini, outside Tehran, Iran. AP

The Islamic Revolutionary Guards Corps: A defensive weapon turned offensive