Will Iran’s proxies in Syria mobilize in support of Hezbollah?

MARSEILLE — For days following Israel’s assassination of Hezbollah Secretary-General Hassan Nasrallah in Beirut on September 27, one question was on the minds of many: How would Iran respond to the crushing blow to its most important regional ally? 

Striking Israel directly meant risking all-out war. Remaining silent would deeply damage Tehran’s reputation with members of its “axis of resistance”—regional actors aligned with Iran and opposed to Israel, which include Lebanon’s Hezbollah, Yemen’s Houthis, Syrian President Bashar al-Assad and a range of proxy militias in Syria and Iraq. 

On Tuesday, Iran gave its answer, launching around 200 ballistic missiles at Israel in what it said was a response not only to Nasrallah’s killing, but also that of Iranian Major General Abbas Nilforoushan in the same strike and the July assassination of Hamas leader Ismail Haniyeh in Tehran.

With Israel and its ally the United States (US) vowing a “severe” response, the region is the closest it has ever been to an all-out war between Iran and Israel. For years, Iran has preferred to keep its hands clean, acting instead through allied forces, not only Lebanon’s Hezbollah—long considered Tehran’s insurance policy in the case of war with Tel Aviv—but also those next door in Syria. 

Tel Aviv certainly considers these forces part of its escalating war, and is increasingly striking targets within Syria even as it launches a ground invasion of southern Lebanon. Over the last week alone, Israel launched well over a dozen airstrikes targeting Hezbollah and other Iran-backed groups, alongside Syrian regime forces and infrastructure. Civilians have also been among those killed.

While Iran answered one question on Tuesday, another remains to be answered: Will it mobilize its allied forces in Syria in support of Hezbollah in Lebanon?

Mobilization of Iranian proxy forces

Iranian-backed groups have mobilized across Syria in the aftermath of Israel’s attack on Lebanon and Iran’s latest attack on Israel, analysts and sources on the ground told Syria Direct. However, some describe these movements as readiness, while others describe redeployment. 

“If there are any movements, they are insignificant so far. The major battle remains in south Lebanon and led by Hezbollah,” Joe Macaron, a global fellow at the Washington-based Wilson Center, said. He added there have been “conflicting reports” of troop movements by Hezbollah and other Iranian-backed groups in Deir e-Zor’s al-Bukamal and the Damascus suburbs.

Iran’s allies in Syria include not only Hezbollah—which intervened in support of Assad following the 2011 Syrian revolution—but an array of Tehran-backed militias with a particularly strong presence in areas such as the country’s eastern Deir e-Zor province along the Iraqi border. 

Hezbollah is now “preparing its forces” in western and central Syria close to Lebanon, Ruslan Trad, a resident fellow at the Washington-based Atlantic Council, said. However, it remains to be seen whether the group will be able to move these forces from Syria to Lebanon given the “logistical risk,” said Macaron. “Israel might strike them while on the move.” 

According to Trad, however, some Iranian-backed groups have moved across the border. “Iran moved some of its subordinate militias to Lebanon, and the operational headquarters of some of the pro-Iranian militias operating in Syria were relocated to Beirut,” he said. 

With continuing escalation between Israel and Hezbollah, as well as between Tehran and Tel Aviv, Trad believes further deployments are likely to occur. “If Hezbollah’s defense[s] began to collapse, these groups in Syria might increasingly intervene to ease pressure on Hezbollah,” Macaron agreed. 

Relative quiet on the southern and eastern fronts

In southern and eastern Syria alike, Hezbollah and other Iranian-backed forces appear to be on the defensive, their movements careful and measured as they seek to avoid Israeli and US-led international coalition airstrikes. 

In southern Syria, “there are no major movements and preparations by the regime and the Iranians…that suggest military action or the possibility of opening a new front against Israel,” one former commander of the opposition Southern Front in Daraa told Syria Direct, requesting anonymity for security reasons. In the past week, Israel has targeted airports and radar systems in southern Syria.

There, if anything, Hezbollah forces appear to be withdrawing from the front lines. “We received information this week indicating Hezbollah made some changes in its positions in Syria, with withdrawals from the Quneitra front,” which borders the Israeli-occupied Golan Heights, the former commander said.

That said, the movements of Hezbollah and other Iran-backed forces are difficult to detect as they occur “under the cover of regime forces, especially the [Syrian army’s] 4th Division,” he conceded. 

The commander of the 4th Division, Maher al-Assad, brother of Syrian President Bashar al-Assad, was reportedly targeted in an assassination attempt near Damascus this week. Some analysts read the strike as a likely message from Tel Aviv to Damascus, warning the regime to remain on the sidelines.

“The Syrian regime does not want to open a front against Israel because it knows that it will bomb the presidential palace if it does so,” the former opposition commander said. He believes the Syrian-Israeli border is likely to remain calm, possibly “limited to some Iranian militias launching some limited-impact drones and rockets,” as in the past.

In eastern Syria, Iranian-backed groups—notably Iraqi factions such as the Popular Mobilization Forces (PMF)—are present in Deir e-Zor, alongside Lebanese Hezbollah. The area is strategically important as part of the land corridor between Iran, Iraq, Syria and Lebanon. Fighters and weapons flow seamlessly across these countries’ borders, interrupted only by Israeli and US-led coalition airstrikes.

“During the last few days, there has been [Iranian proxy] mobilization all along the Euphrates,” one military source from the Syrian Democratic Forces (SDF)-affiliated Deir e-Zor Military Council told Syria Direct. However, actual troop movements have not occurred “out of fear of coalition airstrikes,” the source reported. 

In Deir e-Zor, the Euphrates River serves as a de facto border between the US-backed SDF to the northeast and the Syrian regime and Iranian-backed groups to the southwest. Iranian proxies have targeted SDF and US military bases in Syria and neighboring Iraq since October 7. Several such attacks against US bases in Deir e-Zor and neighboring Hasakah province took place this week, but were not part of Iran’s retaliation against Israel on Tuesday.

One local activist in the Deir e-Zor city of Mayadeen told Syria Direct Hezbollah has evacuated the area of al-Bukamal city and the Iraqi border and moved towards the countryside, fearing airstrikes by US-led coalition forces.

Several high-ranking members of the Iranian Revolutionary Guard Corps (IRGC) have left Syria, the source added. These include al-Hajj Kamil, who heads the brigade for Deir e-Zor province and Syria’s eastern desert, as well as al-Hajj Amer, who is responsible for financial operations. Both are Iranian nationals. 

There have not been any “notable” movements across the Syrian-Iraqi border in recent weeks due to “the [Iranian-backed] militias’ fear of being targeted by US or coalition forces,” Mohanad Faris, a Baghdad-based journalist specialized in Iraqi politics, told Syria Direct.

Faris does not expect Iranian-backed Iraqi militias to mobilize unless Israel directly targets Iran. “Iran does not want to involve its Iraqi arms in this war because of the possibility of being targeted,” he explained. It does not want to lose its “influence” as a “major supporter in Iraq, both politically and economically.”

Supporting Hezbollah

As a tense calm holds across eastern and southern Syria, Iran-backed forces there appear to be on alert, but are not mobilizing to assist Hezbollah directly in Lebanon, at least for the time being.

On Monday, Iranian foreign ministry spokesperson Nasser Kanaani told reporters “there is no need to send volunteer or support forces from Iran to Gaza and Lebanon, as Lebanon and Palestine have the necessary capability to defend themselves.”

As Hezbollah comes under increasing strain, Iran must weigh its own survival against that of its militias. Continued escalation with Israel could provoke an American response that would draw Iran into a wider conflict, Trad explained. 

Still, not providing adequate support to its allies could undermine its image domestically and across the region. “If Tehran does not actively support Hezbollah, it could send a signal to other Iran-allied militias and groups in the region that in times of crisis, Iran may put its own survival and interests above theirs,” he said.

As a result, Macaron interpreted Iran’s missile barrage on Tuesday as a “message”—as much to Israel as to its own proxies—that it will stand up for them.