Potential Delivery Systems for Iran's Nuclear Program

April 9, 2009

Nuclear warheads reach a target using a delivery system or vehicle. Following the production of weapons grade fissile material, and subsequent weaponization of the material, a delivery vehicle would need to incorporate a nuclear warhead device to constitute a nuclear weapon. A viable delivery vehicle program encompasses a range of activities covering design, testing, development and production.[1] Countries most commonly designate ballistic missiles as preferred delivery vehicles. Ballistic missiles deploy in the following manner:

"After an initial powered phase of flight, a ballistic missile leaves the atmosphere (about 100 kilometers) and follows an unpowered trajectory or flight path before reentering the atmosphere toward a predetermined target. Ballistic missile ranges can vary from a hundred or so kilometers to more than 10,000 kilometers."[2]

Since its war with Iraq in the 1980s, Iran began to build a ballistic missile arsenal and develop the technology to attain an indigenous missile production capability. Currently, Iran possesses the largest arsenal of ballistic missiles in the Middle East.[3]  


During the 1980s, Iran financed North Korea’s modified ballistic missile programs in exchange for completed missiles and assistance in developing the Iranian capacity to assemble and produce missile components.[4] For example, North Korea provided Iran with missile engines and helped troubleshoot technical challenges faced by Iran in building its current line of missiles.[5] As a result, Iran designed its primary line of ballistic missiles, the Shahab series, from the base model of the North Korean Nodong missile program.[6] The Iranian military now develops and builds modified, longer-range versions of the Shahab domestically.[7] 

Ballistic Missiles

According to U.S. Director of National Intelligence Dennis Blair, “Iran continues to deploy and improve ballistic missiles inherently capable of delivering nuclear weapons.”[8]  Official Iranian media reports, publicizing ballistic missile tests and military parades showcasing Iran’s hardware, have provided outsiders with the primary source of information on Iran’s missile capabilities – despite the fact that the reports often produce conflicting information and lack independent verification. 

Iran’s Shahab-3 ballistic missiles, with an estimated range between 800 and 1,300 miles, possess a nuclear weapons capability.[9] Iran could use the Shahab-3, for example, to deploy a nuclear warhead with only slight modifications.[10] Given its technical specifications, including a payload capacity of nearly one ton, Iran would consider the Shahab-3 as the “preferred delivery vehicle” for a potential nuclear weapon.[11] After initial tests in 1998, Iran more recently tested the Shahab-3 in the summer of 2008 during a naval war games exercise.[12] Although the exact size of the Shahab-3 missile arsenal remains opaque, an estimate from Janes Defence Weekly contends that after tripling its stock of intermediate range ballistic missiles (IRBMs) during the course of 2008, Iran’s Islamic Revolutionary Guard Corps (IRGC) possesses 100 Shahab-3 missiles.[13]

Beyond the basic Shahab-3 medium-range ballistic missile (MRBM), Iran possesses extended range variants of the MRBM.[14] As noted in 2008 by U.S. Missile Defense Agency (MDA) director Henry Obering, Iran currently pursues “newer and longer-range missile systems and advanced warhead designs.”[15] Iran’s pursuit of missile systems could involve developing indigenous production capabilities – or more simply, importing complete missile systems. In 2005, for example, officials from Ukraine conceded that six “medium-range, air-launched cruise missiles capable of carrying nuclear warheads” were sent from Ukraine to Iran in 2001.[16]

Long-range ballistic missiles, or intercontinental ballistic missiles (ICBMs), possess a range of at least 3,400 miles.[17] Defense Intelligence Agency (DIA) director Lowell Jacoby assessed in 2005 that “Iran will have the technical capability to develop an ICBM by 2015.”[18] If it chooses to develop an ICBM missile capability, Iran would need to overcome various technical limitations. In particular, Iran needs to develop or acquire: multi-stage missile technology, a more powerful propulsion system, a re-entry vehicle able to withstand higher velocities and temperatures, and advanced missile guidance systems.[19] Iran could expedite the development of an ICBM if it chose to acquire technologies—such as a multi-stage capability—from foreign suppliers like Russia, China, or a network similar to A.Q. Khan’s.[20] 

In a February 2009 report, the International Institute for Strategic Studies (IISS) illustrated Iran’s capability to do just that – speed up the development of increasingly sophisticated missile technology.[21] IISS explains that between May 2005 and November 2007, Iran appeared to make the transition from producing a two-ton missile motor to a ten-ton missile motor.  Iran’s relatively quick upgrade from a small motor to a larger one is significant because the process typically has a steep learning curve and requires hardware on export-control lists.  Therefore, IISS argues that the upgrade suggests that Iran received technical assistance and export-controlled hardware from foreign sources.    

Speculative reports regarding Iran’s pursuit of longer range IRBMs and ICBMs have drawn attention in recent years. In 2008, U.S. deputy national intelligence director Thomas Fingar noted Iran’s display of a 1100 mile range missile (Ghadr-1) during a military parade and Iranian claims of a new 1250 mile range missile (Ashura).[22] In November of 2008, the Iranian defense minister declared that Iran tested a new 1,200 mile-range missile – the Sejjil. Weapons expert Duncan Lennox questioned the claim that the missile was new, pointing out the Sejjil’s likeness to the Ashura.[23] Supposedly, the dual-engine, multi-stage Sejjil missile uses solid fuel, unlike the liquid-fueled Shahab.[24] The significance of that distinction lies in that solid fuel missiles launch quicker than liquid fuel missiles and, therefore, are less susceptible to missile defense intercept.[25]       

Speculation periodically surfaces regarding an Iranian ICBM, commonly referring to a Shahab-6.  Recent reports claim that the 3500 mile range Shahab-6, based on North Korea’s Taepodong, is under development.[26] Iran denies it has plans to pursue an ICBM capability, however, it is unclear if Iran actively pursues, previously abandoned or even created the design for a Shahab-6 ICBM.[27]  As Stephen Hildreth of the Congressional Research Service (CRS) notes, “non-official public sources reflect little technical or program consensus regarding an Iranian ICBM program.”[28]

Iran could also use the cover of its space program to develop parallel capabilities for a long range ballistic missile, emulating North Korea’s development of the Taepodong ICBM.[29]  Concerns over such dual-application technology heightened in February 2009 following Iran’s launch of a satellite into orbit using an-Iranian developed rocket.[30]  The technical capabilities utilized in that satellite launch, including placement accuracy and mid-flight separation, can be applied to an ICBM delivery system.[31]

Alternative Delivery Vehicles

As an alternative to the use of the most likely delivery vehicles, ballistic missiles, Iran could deliver a nuclear weapon through nonconventional means exploiting the IRGC’s doctrine of asymmetric warfare.[32] General asymmetric warfare theory refers to scenarios in which one state, or group, seeks to leverage its strengths or manipulate an adversary’s weakness to its advantage.[33] In Iran’s case, for example, the IRGC could transfer a nuclear weapon device to a proxy terrorist organization.  Kenneth Pollack asserts that this scenario remains unlikely because Iran “has never believed that these groups required such weapons [WMD] and because it feared that if their use were ever traced back to Tehran, the retaliation it would suffer would outweigh any gains from the attack [resulting from a weapons transfer] itself.”[34] Additionally, Iran could launch nuclear weapons mated with short-range cruise missiles, which would be ferried to a designated target, or launch a ship carrying a nuclear weapon explosive as the delivery vehicle itself.[35]


[1] Simpson, John, “Iran’s Nuclear Capability and Potential to Develop Atomic Weapons,” in Iran’s Nuclear Program: Realities and Repercussions (Abu Dhabi: The Emirates Center for Strategic Studies and Research, 2006), 24-25.
[2] Hildreth, Steven A., Iran’s Ballistic Missile Programs: An Overview (Washington: Congressional Research Service, July 2008), 2.
[3] Obering, Henry, Testimony before the National Security and Foreign Affairs Subcommittee of the House Oversight and Government Reform Committee, Washington DC, April 30, 2008.
[4] Bermudez , Joseph S., Jr., Proliferation For Profit: North Korea In The Middle East (Washington: The Washington Institute for Near East Policy, July 1994), 19.
[5] Braun, Chaim and Chyba, Christopher F., “Proliferation Rings: New Challenges To The Nuclear Nonproliferation Regime,” International Security 29, no.2 (Fall 2004), 21.
[6] Tenet, George J., Testimony of the Director of Central Intelligence on Current and Projected National Security Threats before the Senate Armed Services Committee, Washington DC, February 2, 1999.
[7] Cordesman, Anthony H., Iran’s Developing Military Capabilities (Washington DC: Center for Strategic and International Studies, 2005), 37.
[8] Blair, Dennis C., Written testimony on the Annual Threat Assessment of the Intelligence Community before the Senate Select Committee on Intelligence, Washington DC, February 12, 2009, 19.
[9] The precise range of the Shahab-3 is subject to speculation with estimates falling within this range.  In 1999, CIA director George Tenet estimated the baseline Shahab-3’s range at approximately 800 miles.  Media reports based on statements made by Iranian officials have claimed its range is 1,200 miles (see, for example “MP Lauds Iran’s Missile Power,” IRNA, July 13, 2008).    
[10] Blair, David “Iran Launches Its Warning To Israel And U.S.,” The Daily Telegraph, July 10, 2008.
[11] Fitzpatrick, Mark, The Iranian Nuclear Crisis: Avoiding Worst-Case Outcomes (London: Routledge, November 2008), 17.
[12] Kessler, Glen, “Iran Launches Nine Test Missiles, Says More Are Ready,” The Washington Post, July 10, 2008.
[13] Alon, Ben-David, “Iran Prepares For War With Missile Production Rise,” Jane’s Defence Weekly, December 17, 2008.
[14] Maples, Michael D., Written testimony by the Defense Intelligence Agency Director on the Annual Threat Assessment before the Senate Select Committee on Intelligence, Washington DC, February 5, 2008.
[15] Obering, 2008.
[16] Kerr, Paul, “Ukraine Admits Missile Transfers,” Arms Control Today, May 2005.
[17] Hildreth, Steven A., Iran’s Ballistic Missile Programs: An Overview (Washington DC: Congressional Research Service, February 2009), 1.
[18] Jacoby, Lowell E., Testimony on Current and Projected National Security Threats to the United States before the Senate Armed Services Committee, Washington DC, March 17, 2005. 
[19] Mistry, Dinshaw, “European Missile Defense: Assessing Iran’s ICBM Capabilities,” Arms Control Today, October 2007.
[20] Brookes, Peter, “The Need For Missile Defense,” Policy Review 151 (October/November 2008), 37-38.
[21] Nicoll, Alexander, ed., “Iran’s Missile Development,” IISS Strategic Comments 15, no.1 (February 2009).
[22] Director of Central Intelligence, “Unclassified Report to Congress on the Acquisition of Technology Relating to Weapons of Mass Destruction and Advanced Conventional Munitions, 1 January to 31 December 2007,” Central Intelligence Agency, 2008.
[23] Nazila, Fathi and Cowell, Alan, “Iran Claims Success In Tests Firing Long-Range Missiles,” The New York Times, November 13, 2008.
[24] “Iran Defense Minister Says Newly Tested Missile’s Range Higher Than Shahab-3,” Fars News Agency, November 17, 2008.
[25] Nicoll, “Iran’s Missile Development.” 
[26] Pagnamenta, Robin, Evans, Michael, and Halpin, Tony, “British Diplomats In Secret Move To Choke Off Iran’s Uranium Supplies,” The Times, January 24, 2009; Mistry, “European Missile Defense.”
[27] Hildreth, Iran’s Ballistic Missile Programs, February 2009, 3.
[28] Ibid.
[29] Brookes, “The Need For Missile Defense.”  North Korea has planned to launch a satellite with a Taepodong-2 ICBM in April 2009.  A similar test in 2006 resulted in a mid-flight failure.  See, for example: Sevastopulo, Demetri and Jung-a, Song, “N Korea Missile On Launch Pad,” Financial Times, March 26, 2009.
[30] Cummins, Chip, Taghavi, Roshanak, and Solomon, Jay, “Iran’s Report Of Satellite Launch Stirs U.S. Concern,” Wall Street Journal, February 4, 2009.
[31] Borger, Julian, “How World Leaders View Iran’s Space Ambitions,” Guardian, February 3, 2009.
[32] McInnis, Kathleen J., “Extended Deterrence: The U.S. Credibility Gap In The Middle East,” The Washington Quarterly 28, no.3 (Summer 2005), 172.
[33] Barnett, Roger W., Asymmetrical Warfare: Today’s Challenge To U.S. Military Power (Washington DC: Potomac Books, 2003), 15.  Barnett further clarifies asymmetric warfare as a situation in which one party can take actions that an opposing party cannot or will not undertake.
[34] Pollack, Kenneth, The Persian Puzzle: The Conflict Between Iran and America (New York: Random House, 2004), 419.
[35] Garwin, Richard L., “Evaluating Iran’s Missile Threat,” Bulletin of the Atomic Scientists 64, no.2 (June 2008), 42.