The Karaj complex is at the center of Iran's missile development industry. [1] Karaj's design center is reportedly part of the Defense Technology and Science Research Center. [2] The complex conducts design research and development for the Shahab missile series, including for the missiles' guidance systems, propellants, and solid and liquid fueled engines. [3]

Many experts, including Anthony Cordesman, believe that the facility at Karaj has received substantial support from Russian and Chinese scientists.[4] Russian authorities reportedly authorized the transfer of a complete SS-4 intermediate-range missile production line to the Karaj facility, including the missile's airframe and engine. [5] UNSCR 1747 imposed financial sanctions on the Karaj complex.

Sources:
[1] Yonah Alexander and Milton M. Hoenig, The New Iranian Leadership, (London: Praeger Security International, 2008), p. 177.
[2] Anthony H. Cordesman, Iraq and the War of Sanctions: Conventional Threats and Weapons of Mass Destruction, (London: Praeger, 1999), p. 411.
[3] Wyn Bowen, "Ballistic Missile Shadow Lengthens," Jane's International Defence Review, 1 January 1997, www.janes.com.
[4] Anthony H. Cordesman, Iran's Military Forces in Transition: Conventional Threats and Weapons of Mass Destruction (London: Praeger Publishers, 1999), p. 255.
[5] Ali Chaudhry, "Iran's Ambitious Missile Program," Center for Defense Information, 1 July 2004.