Heroes of the Islamic Republic: mural of Iranian soldiers in a street in Tehran in April 2019 Rouzbeh Fouladi · NurPhoto · Getty

On 5 May the US announced it was deploying the USS Abraham Lincoln Carrier Strike Group and a bomber task force to the Gulf. National Security Advisor John Bolton said this was ‘in response to a number of troubling and escalatory indications and warnings’ and told Iran that ‘any attack on United States interests or on those of our allies will be met with unrelenting force.’ Tension in the Gulf and on the Arabian peninsula has continued to rise, and Washington’s allies Saudi Arabia and the United Arab Emirates have, with varying degrees of explicitness, blamed Iran for the sabotage of oil tankers near the Strait of Hormuz and the increase in Houthi rebel activity in Yemen.

Bolton went on to say, ‘The United States is not seeking war with the Iranian regime, but we are fully prepared to respond to any attack, whether by proxy, the Islamic Revolutionary Guard Corps, or regular Iranian forces.’ This ominous statement makes it clear that the possibility of armed conflict between Iran and the US, its Gulf allies and Israel, while still only theoretical, cannot be discounted. It is also a reminder that any belligerent attacking the Islamic Republic of Iran will be met by two distinct military forces: the regular army and the Revolutionary Guards. To understand their origins and assess their capability to withstand a US military intervention, it’s necessary to go back 40 years to the days that followed the fall of the shah.

On 12 February 1979 the new Islamic regime in Tehran brutally purged the Imperial Iranian Army, especially its upper echelons, even though it had declared its neutrality: the mullahs suspected that the army remained loyal to the deposed shah, who had fled to Morocco. The regular army was renamed the Islamic Republic of Iran Army (Artesh) and placed under the direct control of a hardline political organisation that served the regime: the Sepah-e Pasdaran-e Enghelab-e Islami or Islamic Revolutionary Guard Corps (IRGC, known informally as the Pasdaran). Originally created from popular militias that supported Supreme Leader Ayatollah Khomeini, the Revolutionary Guards have since served as a counterbalance to the regular army and an effective way to dissuade anyone contemplating a coup. The history of the Islamic Republic, especially its early years, is strewn with plots of varying credibility thwarted by the Revolutionary Guards and followed by bloody purges.

When Iraq invaded Iran in September 1980, barely a year and a half after the Islamic revolution, Artesh got an opportunity to prove its loyalty to its new masters. Retired officers were called up and others, such as pilots who had come under suspicion because they were US-trained, were released from prison and assigned to combat units. Artesh’s successful counteroffensive against the Iraqis led to the port of Khorramshahr being retaken in May 1982, a turning point in the war, and in the course of that summer Iran recaptured all of the territory it had lost to Iraq.

Revolutionary Guards to the fore

But the mullahs soon relegated Artesh to a subordinate role to allow the Revolutionary Guards to acquire military legitimacy. Fanaticism made them want to fight on and overthrow Saddam, but their general offensive against Iraq proved a disaster, with hundreds of thousands killed, and the war ended in stalemate in August 1988.

Since the war, Iran’s military has maintained this dual base, each element having a well-defined role. According to article 143 of the 1979 constitution (amended in 1989), the regular army is ‘responsible for protecting the independence and territorial integrity of the country and the order of the Islamic Republic’. Article 150 stipulates that the Revolutionary Guards ‘will remain in effect to continue in [their] role of protecting the Revolution and its achievements ... with emphasis on fraternal cooperation and harmony among [different branches of the armed forces]’. In reality, Artesh, the regular army, is conceived as a classic defensive force, with four corps: army, air force, navy and, since 2007, air defence. Its main mission is to guard Iran’s borders and protect its territory.

The Revolutionary Guards will remain in effect in order to continue in their role of protecting the Revolution and its achievements ... with emphasis on fraternal cooperation and harmony Iranian constitution, article 150

The Revolutionary Guards went from being a people’s militia to a true army in 1985, with the mission of serving the ideology of the Islamic Republic. Answering directly to the Supreme Leader and led since April 2019 by Hossein Salami, they are estimated to be 150,000 strong; they have access to the best recruits and take the theory of permanent asymmetric warfare to the limit. Through their Quds Force (Al-Quds means ‘Jerusalem’ in Arabic and Farsi), they have the ability to operate in foreign theatres, such as Syria, where they have fought alongside the Assad regime’s forces; Lebanon, where they have supported Hizbullah; and Iraq, where they have backed Shia militias.

The regular army lacks the logistical capability to operate outside Iran’s borders. So in the event of an enemy counteroffensive, the air force would be unable to protect troops or control the skies. Its 350,000 men (200,000 of whom are conscripts on compulsory 18-24 month military service) nonetheless give it a solid territorial base. There is no official summary of its doctrine, but speeches by Iranian leaders at commemorations of Iran’s claimed victory over Iraq emphasise its resilience. Its identity is founded on its success in absorbing the shock of the Iraqi surge in 1980 and turning the situation around after several months of bloody fighting.

A foreign invasion would have to contend with a regular army trained to hold its positions come what may, in addition to the patriotic mobilisation that would undoubtedly occur among the general public. It would also be met by Revolutionary Guards trained to conduct a war of harassment abroad against superior forces and to pose a permanent threat to their enemies and their economic interests. The Gulf offers a wide range of sensitive targets, including oil tankers, desalination plants and foreign warships.

The same defence/offense division of labour between the regular army and the Revolutionary Guards characterises Iran’s air defence strategy. The air force, which has only 65 combat aircraft, some dating from the time of the shah (Northrop F-5 fighters and F-4 fighter-bombers), is Artesh’s poor relation. But the army has one of the world’s best territorial air defence systems, including Russian Rezonans over-the-horizon radar and Avtobaza ground-based passive ELINT systems, as well as many classic Russian and Chinese radar systems.

Yet more significant, Iran, which on paper is able to detect stealth fighters, in 2016 acquired the Russian S-300 surface-to-air missile system, which enables it to defend strategic sites within a 200km range. The Revolutionary Guards also have the mission of developing ballistic capability to deter attack. It is hard to assess Iran’s missile arsenal, but the Revolutionary Guards are known to have at least 300 Shahab-1 and -2 missiles, which have a maximum range of 500km. Some of these missiles, which were designed in the 1980s and manufactured in North Korea, have been updated locally, giving them a range that could threaten US regional bases in the Gulf, Iraq and Afghanistan. According to SIPRI (the Stockholm International Peace Research Institute), Iran also has around 100 missiles with a range of over 1,000km (Shahab-3/Ghadr), some even up to 2,500km (Soumar/Sejjil), which put Saudi Arabia, Israel, and the interior of China, Russia and eastern Europe within range.

A moderate military capability

In a country still marked by the damage inflicted (especially on the cities) by 400 Iraqi missile strikes during the Iran-Iraq war, this ballistic capability makes Iran better able to respond to an attack, or even carry out a first strike, and paralyse an enemy’s ability to retaliate. In addition to these weapons, the Revolutionary Guards’ air force has hundreds of drones, which could be deployed in swarms to overwhelm enemy radar. These drones can carry missiles and have been used by Houthi rebels in Yemen.

Using swarm capability to disorientate the enemy is a possibility in the naval sector too. The US navy knows that in a conflict situation it would face an onslaught of Iranian-built speedboats and midget submarines and ground-effect vehicles (Ekranoplans), designed for sustained, low-level flight over water. Iranian observation drones also filmed US ships, and even aircraft carriers, in the Gulf on several occasions between 2010 and 2017 (1). In mid-May, Saudi Arabia even accused Iran of ordering drone attacks on its oil installations.

Despite all this, it’s important not to exaggerate Iran’s military capability: in 1991 the Iraqi army was classed as the fifth best in the world, before being defeated by international coalition bombardments. Artesh and the Revolutionary Guards do, though, possess considerable financial resources. The 2016 defence budget was $15.9bn, 42% of which went to the Revolutionary Guards. That’s a similar level of spending to Turkey and Israel, but much less than Iran’s other regional rival, Saudi Arabia, whose military budget is $60bn. US, EU and UN sanctions have made Iran a pariah in the international arms market; its main suppliers are China, North Korea and Russia, but Russia’s enthusiasm for selling to Iran fluctuates. In 2016 it refused to deliver 200 Sukhoi Su-30 multirole air superiority fighters and it has delayed supplying S-300 missiles following pressure from the US and Israel.

This ostracism explains Artesh’s chronic state of under-equipment. Its most powerful combat tank is the Russian T-72, designed in the early 1970s (and modernised locally), and the bulk of its armoured division is formed of Patton and Chieftain tanks dating from the Korean and Vietnam wars (1950-53 and 1955-75). The domestic arms industry, built on what remained of the shah’s plans for a western-style military-industrial complex, has struggled to compensate for the effects of the international embargo. Because of their constant activity and presence in foreign theatres, the Revolutionary Guards are a driving force in innovation in this field. Their ballistic missile programme, although inherited from North Korean technology, is a good illustration.