Iran has the largest and most diverse inventory of long-range artillery rockets and ballistic missiles in the Middle East. It is estimated to have between 200 and 300 Scud-B and Scud - C missiles, which Iran has renamed the Shahab-1 and Shahab-2. It also owns hundreds of Zelzal rockets and Fateh-110 semi-guided rockets.
These systems allow Iran to threaten targets throughout the Gulf
littoral, but they are not accurate enough to be decisive militarily. Iran would need at least 100 missiles armed with 500-kilogram conventional warheads - and potentially many more - to destroy a specific target with a moderate level of confidence.
If fired in large numbers, Iranian missiles might be able to harass or disrupt operations at large US or GCC military targets, such as airfields, naval ports or fuel depots. But such attacks are unlikely to not halt activities for a significantly long time.
Iran is also unlikely to be able to improve the accuracy of its short-range missiles for at least the next five to ten years. The addition of more sophisticated inertial guidance units - or Global Positioning System (GPS) receivers - could improve accuracy by only 25% if properly incorporated into a Shahab or Fateh-110 missile, and then thoroughly tested.
To further enhance its accuracy, Iran would have to develop the capacity to terminate missile thrust precisely or add correction systems for the post-boost phase. But adding these mechanisms would also require flight testing likely to take four years or longer.
Iran's longer-range missiles - the Shahab-3 and Ghadr-1 - are capable of striking targets throughout the Middle East, including Israel, as well as portions of southeastern Europe. But these missiles are highly inaccurate. And Iran's stockpile likely totals less than 100.
This could change once Iran completes development of the solid-fuelled Sajjil-2 missile. Iranian engineers are widely believed to have the capacity to manufacture this system, although they still rely on foreign sources for fuel-production ingredients. Development may have stalled, however, since Iran has conducted only one flight test since 2009.
The utility of Iran's ballistic missiles is likely to remain weak for years, yet they could be used effectively as a psychological weapon on population centers. The most vulnerable cities are Baghdad, Kuwait City and Dubai, since they are within range of the Zelzal rockets that Iran has in large quantity. Abu Dhabi, Manama, Doha and Saudi coastal cities are far enough to require the longer-range Shahab-1 and -2 missiles, which are in shorter supply.
What are Iran's air force capabilities? And how do they compare to the US air forces in the Gulf?
The Islamic Republic's air forces and ground-based air defense systems offer limited protection of Iranian air space. They are no match for the combined capacity of the United States and its six Gulf Cooperation Council (GCC) allies. In a prolonged and intensive conflict involving the United States, Iran would have difficulty protecting its strategic assets, including its nuclear facilities, air bases, and command-and-control centers.
An integrated US air defense network would probably prevent Iranian pilots from reaching many military targets within GCC territory, although limited air raids might have some success in the opening days of a conflict. (The GCC includes six sheikhdoms - Saudi Arabia, Kuwait, the United Arab Emirates, Qatar, Bahrain and Oman - that make up most of the Arabian Peninsula.)
Most of Iran's aircraft were purchased before the 1979 Islamic Revolution and are widely considered obsolete. Even Iran's Russian-made MiG-29 and Su-24 fighter-jets, acquired more recently, lack the modern avionics and air-to-air missiles needed to compete with the US and GCC air forces.
In January, Iran unveiled a new stealth fighter-jet (see left). But the presented craft is clearly a model, or mock-up. It is quite small as well, judging from the size of the pilot seated at the controls. The Qaher F-313 appears to be an aspirational system, which is many years from reality. But it does indicate Iran's ambitions.
Iran also lacks sophisticated airborne command-and-warning assets, as well as the secure communications network needed to relay vital threat and targeting information. These deficiencies place Iranian pilots at a severe disadvantage when engaging hostile air forces armed with a complete picture of the airspace.
Perhaps Iran's most significant shortcoming is its limited capacity to maintain airplanes and generate anything beyond one sortie per day for each fighter jet. Iran has a very limited ability to surge its air forces. It would probably be quickly overwhelmed by a combined attack by US and GCC forces.
Despite these and other shortcomings, Iran's air forces and air defenses can still inflict loses on allied air forces, albeit at a minimal rate. Tehran also claims to have mated C-701 and C-801 anti-ship cruise missiles to its F-4 aircraft. If true, these stand-off weapons would allow Iran to attack US warships and commercial vessels in the Gulf with some success.
If Iran modified anti-ship missiles for land attacks, it could target key infrastructure assets located along the Gulf littoral, although the small warheads carried by these missiles would limit the damage.
What are the defense options against Iran's missiles?
Theater missile defenses flooding into the region could blunt the political and psychological effect of Iran's offensive-missile threat. The United States already deploys Patriot, SM-3 and other missile interceptors in the region. Kuwait and Saudi Arabia have older-generation Patriot batteries. Both countries are in the process of upgrading their defenses with more capable systems. The United Arab Emirates leads in acquisition of missile and air defense; it is currently procuring a sophisticated suite of systems, including advanced Patriot and THAAD batteries.
No defensive system is leak-proof. But the anti-missile capabilities acquired by the United States and its GCC allies have proven their efficacy during development and testing. They should help minimize public fear.
Iran might try to overwhelm these defenses by firing missiles in large salvos, as it does during annual military exercises. This tactic might allow a few warheads to reach their destinations, but interceptor missiles would probably protect the most critical targets. An integrated missile defense architecture, if implemented across the GCC in a coherent way, would further reduce vulnerability to salvo tactics.
Iran has claimed it can arm drones with missiles. Is this a significant advancement?
Iran is developing a wide-range of unmanned aerial vehicles. Most of the systems seen so far are slow, have limited maneuverability, and carry small payloads, so are used primarily as reconnaissance and intelligence-gathering platforms.
One notable exception is the Karrar, also known as the "ambassador of death." The Karrar is based on target-drone technology, which was originally used for training air-defense crews. Nonetheless, it carries 500-kg gravity bombs and presents yet another means of delivery that American and GCC forces must track and, if necessary, defeat.
The larger concern, however, is Iran's large arsenal of anti-ship cruise missiles acquired from China. These weapons pose a significant threat to Gulf shipping as well as navies operating near the Strait of Hormuz. Iranian use of anti-ship missiles would significantly escalate any conflict, so Tehran would probably use them only if the regime felt threatened. But their mere existence - and the threat they pose - offers Tehran an effective component for deterring attack by others.
Michael Elleman, senior fellow for missile defense at the International Institute for Strategic Studies and a former UN weapons inspector, is co-author of Iran's Ballistic Missile Capabilities: A Net Assessment. Read Michael Elleman's chapter on Iran's missile program in The Iran Primer.