The Fall of Assad’s Regime Shakes Iran’s Proxy Network Across the Middle East
Editor’s Note: this article is being republished with the permission of the Irregular Warfare Initiative as part of a republishing arrangement between IWI and SWJ. The original article was published on 27 February 2025 and is available here.
Introduction
Not long ago, Iran wielded significant influence across the Middle East, extending its reach from Baghdad to Beirut and Damascus to Sanaa. Through a network of proxies, it encircled its regional adversaries, Israel and Saudi Arabia, creating what many referred to as a “ring of fire.” However, over the past 15 months, this strategic advantage has begun to erode. While ongoing clashes between Israel and Hezbollah have tested Tehran’s deterrence strategy, the most consequential blow has been the sudden collapse of Bashar al-Assad’s regime in Syria.
Iran’s leadership initially downplayed the severity of Assad’s fall, with Supreme Leader Ayatollah Ali Khamenei dismissing it as a temporary setback. Yet, the magnitude of the crisis quickly became undeniable. Just a week after the fall of the regime on Dec. 8, 2024, the Islamic Revolutionary Guard Corps (IRGC) commander General Hossein Salami publicly acknowledged the “bitter event” in Syria, marking a shift from denial to reluctant acceptance. This rare admission showcases the strategic importance of Assad’s regime for Iran’s regional power projection.
With Syria’s role as a conduit for weapons and fighters in jeopardy, Iran faces a major setback in sustaining its irregular warfare capabilities. The ripple effects of this upheaval will extend far beyond Syria’s borders, reshaping regional power balances. For Washington, this moment presents a rare opportunity to recalibrate its Middle East strategy, exploiting Tehran’s vulnerabilities to curb its influence. How Iran navigates this crisis, and how the United States responds, will shape the next phase of Middle Eastern geopolitics.
Why Did Syria Matter to Iran’s Irregular Warfare Capability?
Syria has long been a cornerstone of Iran’s military strategy, which revolves around deterrence and asymmetric warfare, leveraging “low-cost, high-impact” operations. This strategy consists of two main components: conventional military capabilities, such as Iran’s missile and drone programs, and irregular warfare, executed through a network of proxies. Syria played a pivotal role in advancing both aspects of this doctrine.
As Iran’s longest-standing ally in the Middle East since 1979, Syria was among the first to recognize the newly established Islamic Republic. During the Iran-Iraq War, Hafez al-Assad’s government provided Iran with weapons after Libya withdrew its support. According to former IRGC minister Mohsen Rafiqdoust, Syria not only supplied arms directly but also acquired Soviet weapons under its name for transfer to Iran. In 1985, Damascus hosted training for thirty IRGC officers on Scud-B missile production and deployment, laying the foundation for Iran’s formidable missile program.
However, Syria’s most significant contribution to Iran’s military strategy extended beyond conventional arms: it was instrumental in shaping Iran’s irregular warfare capabilities by serving as Tehran’s primary opening to the Arab world. This access enabled the formation of Hezbollah, a cornerstone of Iran’s proxy network. Former Iranian defense minister Hossein Dehghan confirmed that, in 1983, Syria facilitated the IRGC’s Mohammad Rasulullah Division’s relocation to Lebanon, where it laid the groundwork for Hezbollah under Assad’s patronage.
Since then, Syria has been Iran’s key stronghold in the Arab world, a role Bashar al-Assad himself acknowledged by calling it Iran’s “gateway” to the region. This strategic importance drove Iran to invest heavily in preserving Assad’s regime after the civil war, providing loans estimated between $30 billion and $50 billion. Iran has also paid a human cost, with over 2,100 soldiers killed in Syria. Beyond financial and military sacrifices, the war enabled Iran to expand its irregular warfare (IW) strategy, establishing a strong military presence with an estimated thirteen bases and five IRGC divisions across Syria.
Iran’s military presence in Syria granted it a strategic foothold in the Mediterranean for the first time in over a millennium, strengthening its asymmetric warfare against Israel by opening a new front. The formation of proxy groups like the Imam Hussein Brigade exemplified Iran’s reliance on IW through proxies to counter adversaries. This also reinforced Iran’s vital land corridor linking Tehran to Hezbollah in Lebanon, ensuring a steady arms supply to its primary proxy. Beyond logistics, Iran has transformed Syria into a military production hub for Hezbollah, reportedly using the Scientific Studies and Research Center (CERS) to manufacture precision-guided missiles, enhancing Hezbollah’s arsenal. In essence, Iran has leveraged Syria not only as a transit route for arms but also as a weapons manufacturing base, deepening its capacity for IW in the region.
Now, with Syria’s role as a weapons hub in decline, the collapse of the 1,574-kilometer land corridor between Iran and Hezbollah will most assuredly disrupt Iran’s arms logistics. Without it, Iran would have to rely on smuggling, maritime shipments, or airlift, all vulnerable to Israeli interception. While Iran has experience using illicit trafficking routes, evidenced by documents showing its covert smuggling networks into the West Bank, the loss of Assad’s regime should create major obstacles. A hostile new Syrian government would likely intensify efforts to block such shipments, further crippling Iran’s ability to sustain its IW strategy in the region.
Hezbollah in the Absence of Assad’s Regime
For Iran and Hezbollah, the loss of Syria as a logistical hub could not have come at a worse time. In the absence of Assad’s regime, Syria is no longer securing or facilitating supply routes, leaving Tehran with significant obstacles in delivering arms and reinforcements to its most important proxy. This comes as Hezbollah finds itself in one of its most vulnerable states, urgently needing support to rebuild. Since the escalation of clashes with Israel in October 2023, the group has suffered devastating losses. Nearly all of its senior leadership, including Secretary-General Hassan Nasrallah, senior commander Fuad Shukr, designated successor Hashem Safieddine, and intelligence chief Hussein Ali Hazimeh, has been eliminated. Hezbollah’s militia has also lost about 4,000 elite fighters and half of its arsenal, leaving it in a precarious position just as Iran struggles to maintain its supply lines.
These setbacks have reportedly created a power vacuum within Hezbollah, increasing the risk of internal divisions. According to Lebanon’s Al-Nahar newspaper, some factions argue that Hezbollah should focus on rebuilding itself rather than aiding the Axis of Resistance, while others disagree.
The decline of Assad’s regime could pose a significant threat to Hezbollah’s operational capacity. Any blow to Hezbollah would also impact Iran’s IW across the region, as Hezbollah has been one of the primary enforcers of the growth of Iran’s proxy network in Syria, Iraq, and Yemen.
Hezbollah’s Operation Code 110 in 2013 marked the start of its extensive military involvement in Syria, securing key victories that helped Assad’s regime withstand the early phases of the civil war. The group played a decisive role in capturing strategic areas such as Al-Qusayr, the Damascus-Homs Corridor, the Qalamoun region, and parts of northern Syria. Beyond Syria, Hezbollah was instrumental in training and arming Shiite militias in Iraq against United States’ forces. Some reports suggest that after the 2020 killing of IRGC Quds Force commander Qassem Soleimani, Hezbollah’s leader Hassan Nasrallah took on a managerial role in overseeing Iran’s operations in Iraq. In Yemen, Hezbollah has been pivotal in training the Houthis, enhancing their military capabilities and reinforcing Iran’s influence in Yemen and the broader Gulf region.
Lastly, Hezbollah remains a dominant force in Lebanon, itself a key source of regional instability. Hezbollah’s military wing has been stronger than the Lebanese Army, challenging the Lebanese government’s monopoly on the use of force, and its financial capabilities have often surpassed the government’s. The militia has even held the largest gold reserves in the country, which allow it support its activities as a key vanguard for Iran’s interests in the region.
Given this context, Assad’s fall stand to significantly weaken Iran’s asymmetric warfare by crippling Hezbollah, its key non-Iranian enforcer.
The Probability of The Domino Effect
The fall of Assad’s regime could extend beyond weakening Hezbollah and Iran’s influence in the Levant, potentially destabilizing Iran’s entire proxy network. Iraq, in particular, presents a critical front, as Syria’s border with Iraq’s Sunni-majority Al Anbar region raises concerns of a spillover effect. A Sunni-led Syrian government backed by Hay’at Tahrir al-Sham (HTS) could fuel a Sunni insurgency in Iraq, further undermining Iran’s regional strategy.
HTS has deep ties to Iraq. Many of its senior commanders, including leader Ahmed Hussein al-Sharaa, began their activities during ISIS’s offensive in Iraq. This history has given the group familiarity with Iraq’s geography and likely connections to discontented Iraqi Arab Sunnis opposing Iran-backed Shia dominance. This threat is not hypothetical. Fighters and weapons have flowed from Syria into Iraq during past conflicts, including the Sunni insurgency of 2003-2008 and the resurgence of ISIS in 2014.
The situation today is more precarious for Iran than it was in either 2003-2008 or 2014. With the fall of Assad’s regime and the significant blow Israel has dealt to Hezbollah, the operational capacity of the Axis of Resistance is at its weakest point. A renewed Sunni uprising in Iraq inspired by Syria’s regime change would pose a severe challenge to Iran’s regional influence. Political change in Syria could also inspire a Sunni uprising in Lebanon where 31% of the population are Sunnis, many feeling sidelined by Hezbollah. A Sunni-led Syria might encourage such an uprising, giving discontented Sunnis hope of regaining control of Lebanon.
This scenario is plausible, as Syria has historically been a key influencer in Lebanon. Even during the friendly relations between Iran and Hafez al-Assad’s Syria, Damascus sought to limit Iran’s influence in Lebanon. Syria at times backed Hezbollah’s intra-Shia rival, the Amal Movement, and even clashed with Hezbollah militants, as seen in 1987 when Syrian forces opened fire on them. Competition between Iran and Syria persisted until Bashar al-Assad’s presidency in 2000. His leadership brought Syria into closer alignment with Iran and Hezbollah, making the collapse of his regime even more damaging for Iran. The situation vis-à-vis Lebanon could be far more severe for Iran today, considering Hezbollah’s weakened state. Indeed, the group’s de facto leader, Naim Qassem, reportedly does not feel safe in Lebanon and has relocated to Iran.
Conclusion
The collapse of Assad’s regime presents a serious threat to Iran’s IW capabilities, weakening a key pillar of its regional influence and deterrence strategy. Without Syria as a secure logistical hub, Tehran faces mounting challenges in sustaining its proxy network and maintaining its strategic reach across the Middle East.
In response, the Iranian government has two primary options. It could attempt to de-escalate tensions by negotiating with the United States, buying time to recover from its current vulnerabilities. Alternatively, Tehran may choose escalation, potentially by doubling down on its nuclear program or expanding proxy conflicts elsewhere to offset its losses in Syria.
Another likely course of action is for Iran to strengthen ties with more radical factions or foster insurgencies as a substitute for its diminished foothold in Syria. A precedent for this exists in Iran’s support for Hamas over the Fatah-led Palestinian Authority, as Hamas’ more radical and anti-Western stance made Hamas a more willing partner for Tehran.
In comparison to Fatah, Hamas, which was ideologically closer to Iran, proved to be a suitable proxy for Iranian sponsorship and supply. Similarly, Iran might seek to exploit HTS’s recent efforts to purge Syria’s security forces of Assad loyalists. These purges, which have led to the arrest of many Alawite figures, could provide an opportunity for Iran to support insurgent groups or establish alliances with disgruntled elements in Syria.
Given these risks, the United States must remain vigilant, as Iran has incentives to exhibit both destructive and constructive behavior. In the meantime, Washington must understand that the degraded operational capacity of Iran’s proxy network has opened opportunities. Specifically, there is an opening for the United States to push back against Iran’s surrogates in Iraq and Lebanon by empowering their domestic governments to serve as a counterbalance to Iran’s proxy network. In the absence of an effective and functional state that holds a monopoly over the means of violence, the armed forces, militias, and non-state actors will find the space to emerge. Simply put, non-state groups step in when the state is either incapable of governing a region or providing security. Washington can capitalize on this by fostering regional cooperation, particularly between Israel and Arab nations.
Such cooperation has been proven possible: in April 2024, a coalition including Israel, Jordan, France, Germany, and the United States successfully countered Iran’s aerial attack on Israel. Coalition-building efforts should reach beyond military operations and include intelligence-sharing and covert activities and involve key regional players like Saudi Arabia, Israel, and Egypt. Rolling back the Iranian proxy network would not only contain Iran’s influence but also strengthen Washington’s leverage in regional negotiations, increasing the likelihood of securing strategic concessions from Tehran.
The views expressed are those of the author(s) and do not reflect the official position of the Irregular Warfare Initiative, Princeton University’s Empirical Studies of Conflict Project, the Modern War Institute at West Point, or the United States Government.
