The Defence Industries Organisation (Persian: سازمان صنایع دفاع جمهوری اسلامی ایران, "Organization of Industrial Defense of the Islamic Republic of Iran") usually referred to as DIO, is a defense conglomerate wholly owned by the Iranian Ministry of Defense. It is a reorganized form of the Military Industries Organisation, MIO, which was set up in the Imperial State of Iran. Following the Iranian Revolution and the subsequent Western arms embargo, DIO was created in 1981 to reunite what was left of MIO as Iran worked to set up a domestic arms industry.
Much of DIO's early work was simply reverse-engineering foreign designs (both Western and Soviet) and reworking them where necessary for local production, but over time it has gone from direct copies, though derivatives and on to novel designs. Their first products were based on Western arms supplied to Iran either before the Revolution or during the Iran-Contra affair. While it initially only produced weapons for Iran itself, as Iranian industry grew DIO soon started producing weapons for export.
Today DIO is involved primarily in production of equipment for land warfare, including tanks and armored vehicles, missiles, artillery and rocket systems, smallarms, NBC gear, ammunition and explosives. They also manufacture fast patrol boats.
DIO has been repeatedly accused by the UN of arms exports in violation of various embargoes and treaties, and the UN Security Council has implicated them in manufacturing composite centrifuge rotors for the Iranian nuclear program.