Photo: Emanuele Mazzoni/Adobe Stock
What if Iran overplays its hand in the current conflict and the United States determines that regime change through a large-scale, boots-on-the-ground operation is the only way to restore regional and economic stability? Beyond the conventional warfighting challenges and costs associated with a ground invasion of Iran, the U.S. military would likely face a protracted insurgency led by the Islamic Revolutionary Guard Corp (IRGC) after Iran’s conventional defeat. The challenges associated with a potential counterinsurgency operation in Iran would pale in comparison to the recent U.S. wars in Afghanistan and Iraq. Likewise, numerous environmental factors would impede U.S. political goals, such as establishing an Iranian regime more amenable to U.S. interests.
Iran has been preparing its invasion defenses for decades and has the requisite terrain, force size, armament stockpiles, and combat experience to carry out an effective insurgency. Recently, the IRGC has been mobilizing the masses, arming and training Iranian citizens as young as 12 years old to fight an invading force. If the United States were to occupy Iran, the IRGC and Basij “popular forces” would likely conduct the following actions to preserve the country’s Islamic Revolution, with hopes of waiting out occupiers until the regime could once again regain power:
Iran frequently applies historical lessons learned from past conflicts to its military doctrine. Over recent decades, Iran has gained firsthand experience in numerous theaters across the Middle East by actively supporting proxy organizations and confronting U.S. regional stability efforts. Additionally, observations from the Afghanistan and Iraq wars demonstrated that insurgent warfare levied against a superior conventional adversary can generate strategic victory. An asymmetric strategy fueled by an angry population with ample resources can make an occupier’s sustainment of conflict politically infeasible. Thus, Iran plans to focus its invasion defense strategy on protracted irregular warfare, were it to suffer a conventional defeat.
Over the short term, an IRGC-led insurgency would execute a two-pronged strategy: internal anti-occupation efforts and external force projection. Within Iran, the insurgents would quickly transition from conventional denial to long-term asymmetric disruption of U.S. stability operations. Unlike other authoritarian militaries, which are heavily centralized and bureaucratic, Iran has adopted a decentralized mosaic strategy. This system parallels aspects of the U.S. military, in that lower-ranking subordinate leaders can make real-time mission decisions based on their commanders’ intent without having to wait for senior leaders’ guidance.
By flattening the organizational structure and by delegating command authority, the IRGC could effectively turn each region into its own localized insurgency. Given how many Iranian leaders have been killed by U.S. and Israeli forces, a decentralized strategy ensures that the loss of senior leadership does not harm the insurgency’s overall mission. This strategy also makes prospects of a quick U.S. victory highly unlikely.
The IRGC would likely look to use its surviving missiles, proxy forces, and remaining Quds Force operatives outside of Iran to wreak havoc. Targeting U.S. military rear-support areas outside of Iran could force a reposturing of resources, slowing down forward operations. Bases such as Al Udeid Air Base in Qatar, Camp Arifjan in Kuwait, and Naval Support Activity Bahrain could all continue to be Iranian targets, even after conventional operations cease.
The IRGC has been known to carry out terror operations in over 40 countries. Iran may terrorize regional and global allies during an insurgency scenario. Iran could repurpose some of its 400 kilograms of nuclear material into a dirty bomb to cause societal panic or make specific operational areas temporarily uninhabitable. A dirty bomb would not cause anywhere near as large a blast radius or nuclear fallout zone as a fully enriched nuclear weapon, but it would have a profound psychological effect. Insurgents’ goal in targeting external civilians would be both punishment and discouragement of future international support to the United States. This, however, could have the exact opposite effect, uniting more countries to support the war effort against Iran and turn Iranians against the insurgents.
From a long-term perspective, Iran’s asymmetric strategy would purposefully draw the conflict out to drain U.S. resources, morale, and political support to continue the occupation. As the Taliban axiom goes, “The Americans may have the watches, but we have the time.” Every day insurgent forces survive in an insurgency scenario is another day closer to the reinstatement of the Islamic Revolution in Iran.
Iran presents a formidable global environment for any invading foreign force. Its mountainous geography matches that of Afghanistan’s, but with large urban areas and deserts similar to Iraq. Iran’s geographic size is nearly one and a half times larger than Afghanistan and Iraq combined, with a similar combined population size of 93 million people. Iran also has approximately 1,500 miles of coastline and islands, which would present new challenges for the U.S. military that it did not encounter in Afghanistan or Iraq.
Massive geographic areas provide space and time for insurgent forces to attack, retreat, and repeat. This strategy maximizes survivability while allowing for a steady flow of disrupting attacks against occupiers’ stabilizing efforts. Iran’s mountainous geography, for instance, has tunnels and bunker systems scattered throughout, which it likely uses to store considerable stockpiles of arms and ammunition.
Relying on its assortment of mobile missiles, drones, sea mines, and armed fast boats, the IRGC could continue to carry out attacks on U.S. forces and civilian infrastructure both inside and outside of Iran. In vulnerable waterways, the IRGC would likely use a mix of sea-based and land-based weapons systems to continue disruption of the Strait of Hormuz and, by proxy, the Bab al-Mandeb Strait and potentially the Suez Canal. If the insurgents and proxy forces proved capable of sustaining disruptive attacks, they could severely affect oil flows and impact global economies.
Iran’s human geography also presents a formidable challenge. Of the 93 million, ethnically fragmented people of Iran, 15 million reside in Tehran, Iran’s capital city. Estimates indicate that a force size between 375,000 and 600,000 counterinsurgents would be required to stabilize Tehran. The higher end of the estimate would represent 28 percent of the total current U.S. military (2.1 million) to pacify Iran’s capital alone. To put these numbers into perspective, at the peak of the U.S. occupation of Iraq, the United States had 160,000 counterinsurgents present, which represented 7 percent of the total force in 2007. Successful stability operations in Tehran alone would likely require at least double the 2007 force numbers.
In the absence of a force size increase, a counterinsurgency operation in Iran would likely be broken into smaller regional sections, stabilizing one region at a time. This, however, is what the insurgents would hope for. Retaining some geographic space as a safe haven would aid long-term insurgent survivability.
In his manuscript On Protracted War, Mao Zedong says that “the richest source of power to wage war lies in the masses of the people.” This is the linchpin of Iran’s protracted strategy: During the Iran-Iraq War in the 1980s, it successfully recruited approximately 2 million Basij fighters and united both pro- and anti-revolution Iranians to stop the invading Iraqi force. Iran hopes to achieve similar mass mobilization results for a U.S. invasion scenario. However, environmental dynamics nowadays are more nuanced than in the 1980s.
While Iran’s “hard” support from volunteer and conscripted fighters is likely to be sizable during a hypothetical insurgency, like it was during the Iran-Iraq War, its “soft” support from the local population would not be as robust as in the 1980s and would likely only be modest. Sustainment of an insurgency is traditionally underpinned by both hard and soft support. With only one, a force’s ability to fight and contest an occupying force would suffer. An insurgency’s soft support, for instance, relies on non-combatants to provide insurgent forces safe haven, weapons and ammunition storage, intelligence, information couriering, medical care, and financial support. A population that objects to insurgents’ goals or methods can cut vital lifelines and endanger their long-term sustainability.
Based on the Group for Analyzing and Measuring Attitudes in Iran 2026 reporting, an Iranian insurgency would likely receive estimated soft support from 20–40 percent of the population. Other estimates, such as from former Secretary of Defense James Mattis, indicate that such support could be closer to 10–20 percent. This means that 9–37 million Iranians would likely support the insurgency. Of course, this is assuming U.S. military action would not increase negative public opinion, as occurred during the Iraq War.
While force estimates for a theoretical Iranian insurgency are sizable, they are commensurate and sometimes lower than insurgents’ soft support during the conflicts in Afghanistan and Iraq. In Afghanistan, polling from 2009 to 2016 indicates that public sympathy for armed insurgents decreased from 56 percent in 2009 to 16 percent in 2016. In Iraq, nationwide insurgency support at its height in 2007 was approximately 63 percent, or 17.5 million people, with upwards of 94 percent of the Sunni population supporting the insurgency. While the estimates for Iran are relatively moderate, based on a U.S. Army War College study, resistance movements may only need 15 percent of the population to prove successful. If this is the case for a hypothetical Iranian insurgency, then current estimates indicate the chances for the United States to have favorable conditions during stability operations in Iran are at best a coin toss.
In terms of hard support, estimates indicate that up to 10 percent of Iran’s population would be willing to fight. Given that Iran has approximately 33 million military-age males, this would mean that roughly 3.3 million Iranians could take up arms willingly. Based on prewar numbers, Iran already poses a trained fighting force of 1.2 million personnel, coming from its conventional Artesh, IRGC, and Basij forces. The additional 2 million “volunteer” fighters directly correlate to its recruitment numbers of Basij during the Iran-Iraq War. While not all of these fighters would be well trained, they would still present formidable insurgent numbers for military planners.
The IRGC’s single largest source of external support is its regional proxy forces, whose numbers hover around 200,000. They are split predominately across Iraq’s Popular Mobilization Forces, Lebanese Hezbollah, Yemen’s Houthis, Gaza’s Hamas, and Syrian groups. Iran would likely attempt to leverage its proxies during an insurgency to provide foreign fighter reinforcements in Iran as well as generate regional and global disruption. Many of these forces have been trained in insurgent warfare and have been provided asymmetric weapons by the IRGC. However, while most of these groups are normally quite capable of coordinated attacks and societal disruption, there is speculation as to their current combat effectiveness due to recent U.S. and Israeli military campaigns.
Although Iran has been preparing its invasion defenses for years, including stockpiling arms and weapons, it would at some point need to be resupplied. Raids and bombings of cache sites would likely deteriorate Iran’s attack capability over time due to the reduced numbers of small arms and munitions available. This would force the IRGC to seek external support, though it is unclear how much Iran could expect.
While Russia is expected to provide Iran with weapons and intelligence to enable kinetic targeting, as well as potential safe haven for Iran’s key leaders, it would likely not go much beyond that. Russia’s focus on Ukraine diminishes the amount of material support it could provide to an Iranian insurgency. China’s support would likely not be much more than Russia’s, given its foreign policy of noninterference and expected economic ramifications, due to U.S. secondary sanctions and declining oil trade. Supplying significant numbers of Chinese arms and munitions to Iran would also take away from China’s principal defense goal of reunifying with Taiwan. However, some claim that China would have much to benefit from the U.S. military being decisively engaged in the Middle East and thus might offer more support than expected.
Regardless of support level, flowing resources and fighters into Iran would likely not be a significant challenge for insurgents. Iran’s over 3,000 miles of land borders with countries such as Afghanistan and Pakistan and nearly 1,500 miles of coastline present ample opportunity for long-term logistics sustainment. By comparison, the U.S.-Mexico border is nearly 2,000 miles long. During the Afghanistan war, arms dealers and criminal traffickers routinely relied on smuggling routes to bypass U.S. and coalition forces. The porous Iran-Afghanistan border enabled criminals to continue their illicit financial gain and allowed the Taliban to sustain its forces. Many of the same routes would likely be used during an Iranian insurgency.
Iran’s preparation for prolonged confrontation in both present day and in a hypothetical insurgency scenario is a reality U.S. planners will have to grapple with going forward. While the wars of Afghanistan and Iraq provide unique and relevant comparisons for a potential Iranian insurgency, they are not completely analogous. Insurgencies often evolve as occupiers adapt to the threat landscape, and the tactics and weapons of yesterday will most certainly not be the same tomorrow.
While toppling Iran’s regime and conventional force would likely not be the U.S. military’s main obstacle, what comes afterwards would be immensely challenging. A potential counterinsurgency operation in Iran would be a very long and hard-fought road to translate military actions into strategic political gains. As with any war though, once the first shots are fired, it is anyone’s guess how it will evolve or end.
Andrew Faulhaber is a visiting fellow in the Intelligence, National Security, and Technology Program at the Center for Strategic and International Studies in Washington, D.C.
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