The Reshaping of Iran’s Axis of Resistance

The fall of the Bashar al Assad regime in Syria marks the end of the greater Iranian project in the Levant for the foreseeable future. Iran has invested tremendous energy and resources over the past decade to build its influence and presence in Syria. This presence helped Iran project force westward and move materiel to proxy and partner forces around the Israeli periphery. The sudden loss of Assad deprives Tehran of its main entry point into the Levant and upends the core assumptions and ideas that have long underpinned Iranian strategy in the Middle East. This defeat comes as the other main pillars of Iranian influence in the Levant—Hamas in the Gaza Strip and Hezbollah in Lebanon—are badly diminished from months of fighting the Israel Defense Forces (IDF). These dynamics amount to the collapse of the Axis of Resistance’s western front.

The fall of Assad reverses the gains made from Iranian policy toward Syria since 2011. Iran intervened at the beginning of the Syrian civil war in order to keep Assad in power, expand land access to Hezbollah, and prevent the conflict from jeopardizing the Axis of Resistance networks in Iraq and Lebanon. Major General Qassem Soleimani organized a military coalition of Axis of Resistance parties to fight the so-called “Islamic State” and Syrian opposition.[i] Soleimani commanded this coalition through the bloodiest stages of the conflict and would later oversee the entrenchment of Iranian and Iranian-backed forces in Syria at unprecedented levels. This military presence, which lasted up until the fall of Assad, enabled the Islamic Revolutionary Guards Corps (IRGC) to operate freely across much of the country and to move weapons into Lebanon and the West Bank via Jordan. The IRGC also tried to move forces near the Israeli-controlled Golan Heights and station air defense systems and strike capabilities across Syria in order to defend against and threaten Israel.[ii]

The fall of Assad deprives Iran of these military and strategic benefits and will severely undermine future Iranian efforts to rebuild Hamas and Hezbollah. The opposition groups that are consolidating power in Syria are hostile to Iran, especially given the historic Iranian role supporting Assad and his brutality. Iran could find itself on overtly adversarial terms with the future Syrian government, depending on which specific groups gain control. And the expulsion of Iranian influence from Syria will make it extremely difficult for the IRGC to transfer the resources needed to help Hamas and Hezbollah recuperate rapidly at scale.

The collapse of the Axis of Resistance’s Levant front comes as Iran itself is increasingly vulnerable. The airstrikes that the IDF conducted into Iran in October 2024 disrupted the Iranian ability to produce solid-propellant ballistic missiles and neutralized the most advanced Iranian air defense assets—the Russian-sourced S-300s.[iii] These airstrikes thus diminished the Iranian ability to defend against and retaliate for conventional attacks. Iranian authorities separately face a worsening internal security crisis (although discussions of a possible revolution or the overthrow of the regime are premature). Large swaths of the Iranian population have come to the streets in recent years to protest against the Islamic Republic and call for revolutionary change. These protests have become more coordinated and violent, especially since 2022, and stretched the ability of the regime to control them.[iv] These protests are showing no indication of turning into an insurgency. But they impose additional costs and pressures on the regime that undermine its ability to respond as it would like to external challenges. The regime has, moreover, lost many of the key leaders on whom it would rely to manage these myriad external and internal crises. The IDF has killed several influential IRGC officers, who were trusted by the Iranian supreme leader, in airstrikes in Damascus and Beirut in recent months, while also killing Ismail Haniyeh, Yahya Sinwar, and Hassan Nasrallah.[v]

It is unclear how Iranian leaders will respond to these challenges in the long-term, but they will likely in the short-term prioritize shifting the center of gravity of the Axis of Resistance eastward to Iraq and Yemen. Iran is more reliant than it has been in years on the ability of its proxies and partners to deter the United States and Israel. Iran will likely spend the coming months and years trying to deepen its control over these groups and outfitting them with increasingly advanced strike capabilities. Iran will also likely explore how to prevent efforts to dislodge its proxies and partners from Iraq and Yemen. Iranian leaders have almost certainly learned from their experiences watching the Islamic State march on Mosul in June 2014 and Syrian opposition forces march on Damascus more recently that they must keep their proxies and partners secure domestically.

The United States should exploit Iran’s current vulnerability and weakness to push back on the Axis of Resistance in Iraq and Yemen. Doing so would include increasing support for—rather than abandoning—Iraqi leaders who wish to see their country independent of Iranian influence and subversion. It would also include destroying the willingness of the Houthis to continue attacks on international shipping rather than conducting intermittent airstrikes on their capabilities.[vi] Ceding Iraq and Yemen, on the other hand, would allow Iran and its Axis of Resistance the space and time to recover. Tehran and its allies may be down. But they are just as committed as before to attaining regional hegemony, destroying the Israeli state, and expelling American influence from the region. The United States and its allies and partners in the region should capitalize on the positive momentum created by the fall of Assad.

[i] https://www.understandingwar.org/backgrounder/irans-new-way-war-syria

[ii] https://jusoor.co/en/details/mapping-the-iranian-militarys-footprint-in-southern-syria ; https://www.newsweek.com/exclusive-iran-keeps-building-air-defense-network-syria-israel-keeps-bombing-it-1772013 ; https://eyeofeuphrates.com/ar/news/2021/10/01/3376 ; https://sethfrantzman.com/2019/12/12/everything-you-need-to-know-about-irans-imam-ali-base-at-albukamal-syria

[iii] https://www.criticalthreats.org/analysis/the-consequences-of-the-idf-strikes-into-iran

[iv] https://www.hudson.org/mahsa-amini-protests-defeat-islamism-iran

[v] https://www.reuters.com/world/middle-east/israeli-air-strike-syria-kills-senior-iranian-revolutionary-guards-member-2023-12-25/ ; https://www.theguardian.com/world/2024/apr/02/mohammad-reza-zahedi-who-was-the-iranian-commander-killed-in-an-israeli-strike-in-syria ; https://iranwire.com/en/politics/134463-abbas-nilforoushan-who-was-the-irgc-commander-killed-in-beirut/

[vi] https://www.aei.org/research-products/report/ending-the-houthi-threat-to-red-sea-shipping/