The Defense Industries Organization (DIO) is a conglomerate of companies run by the Islamic Republic of Iran whose function is to provide the Armed Forces with the necessary manufacturing capacity and technical abilities.

In 1973, the Iran Electronics Industries (IEI) was founded to organize efforts to assemble and repair foreign-delivered weapons.

Over the next fifteen years, military plants produced small arms ammunition, batteries, tires, copper products, explosives, and mortar rounds and fuses.

In addition, helicopters, jeeps, trucks, and trailers were assembled from imported kits in attempts to transfer technical knowledge to Iran.

Plagued by the upheavals of the time, the MIO was left unable to operate without foreign specialists and technicians; by 1981 it had lost much of its management ability and control over its industrial facilities.

In late 1981, the new revolutionary government of Iran brought together the now disorganised sections of the MIO and placed them under the Defense Industries Organization.