Iran is trying to mobilize regional fighters to help support Syrian President Bashar al-Assad while it has deployed members of Hezbollah and Iraqi Shiite militias to Syria, soldiers and commanders said in Washington Post, noting that they await orders to fight.

Assad’s forces are struggling to prevent a surprise advance by Islamist rebels who have seized the city of Aleppo and nearby towns and villages. The last time Syria’s civil war threatened Assad’s rule, Hezbollah’s ground forces were instrumental in toppling it.

But with the Lebanese group’s fighting capabilities significantly degraded by the war with Israel, it is unclear whether it has the will or ability this time to substantially change the direction of the conflict. While Iraqi militias could potentially fill some gaps, analysts say they have less training and inferior equipment.

The sudden resurgence of the Syrian conflict after years of frozen battle lines has put further pressure on Iran’s self-styled “axis of resistance” – the armed proxy alliance it has long relied on to protect its interests in the region. Syria is one of Tehran’s closest allies, with vital supply lines on its soil allowing it to send money, weapons and advisers to Hezbollah. If Assad falls or his power is reduced, Iran will not be able to help rebuild Hezbollah.

Hezbollah is the centerpiece of Tehran’s proxy network, as it is Iran’s indirect response to regional conflicts without the need for Tehran to be directly involved. With the team now suffering significant losses Iran is drawn into direct confrontations with Israel.

“Iran has been there for us and protects the oppressed,” said a Hezbollah member who, like others in this story, spoke on condition of anonymity to discuss the ongoing military operations. “We are allies and always will be,” he added, dismissing concerns that Hezbollah is too weak to join the fight in Syria.

Lebanese and Iraqi fighters deployed in Syria are operating in a “defensive” posture, according to the Hezbollah member and Iraqi commanders, though they are ready to engage more actively if orders change.

In the past, Iran has also turned to Afghan fighters from the country’s Hazara minority, as well as Shiite fighters from Pakistan, although analysts say these groups operate more as mercenaries than traditional armies, and it is unclear what role they can play in Syria.

The Iranian government has not committed to deploying its own soldiers without ruling it out, currently relying on its network of military advisers from the Islamic Revolutionary Guard Corps (IRGC) embedded throughout the country.

“If the Syrian government asks us to send forces to Syria, we will study their request,” Iranian Foreign Minister Abbas Araghtsi said Tuesday in an excerpt of an interview posted on his official Telegram channel. For now, at least, the country appears to be relying on its proxies to hold the line.

Syrian government forces are currently targeting rebel strongholds in Hama, a central city located between Damascus, the capital, and the city of Aleppo, which opposition fighters captured last week. The battle is being waged by Hayat Tahrir al-Sham, or HTS, an Islamist group that was formerly an al-Qaeda arm and is still designated a terrorist group by the United States.

The HTS advance coincided with a ceasefire agreement in Lebanon, following months of retaliatory Israeli airstrikes that killed most of Hezbollah’s senior leadership and a ground offensive that destroyed much of its military infrastructure.

Hezbollah fighters have been heavily deployed along Lebanon’s borders to the cities of Hama and Homs, according to the Hezbollah member. Iraqi commanders say their fighters are mainly in eastern Syria, where the Syrian Democratic Forces, a Kurdish-led rebel group backed by the United States, have taken advantage of the chaos to seize government-held villages near Deir al-Zour.

“The priority now is securing the border,” an Iraqi commander told The Washington Post. Iraq’s Shiite militias are deeply intertwined with the country’s government and armed forces, and officials in Baghdad have expressed concerns about a possible spillover of violence from Syria.

Another major player is Russia, whose intervention in the Syrian war in 2015 gave the government an overwhelming advantage with its air power. Moscow maintains bases in Syria and has carried out raids in recent days against rebel and civilian targets in the HTS headquarters in Idlib. When asked on Monday whether Russia would increase its air support for Assad, the Kremlin said it was analyzing the situation.

“Iran’s ability to mobilize these disparate groups is really important, because Russia has the air power to support them, but not the ground forces,” said Nicole Grajewski, an expert on Iran-Russia relations and a fellow at the Carnegie Endowment.

When Russia sent fighter jets into Syria nearly a decade ago, Iran already had thousands of fighters on the ground with established spheres of influence and command protocols. This time, he said, it is unclear whether Iran will be able to match or effectively manage such a force.

“Iran’s role in Syria is arguably more important now than it was before,” Grajewski said. Despite years of support from Russia, Syrian government forces are finding it difficult to operate on their own, he said, an assessment borne out in Aleppo, where the Syrian army appeared to be crumbling in the face of rebel attacks.

Analysts say Iran’s proxy network has never fully recovered from the death of top commander Qassem Soleimani, who was killed in a 2020 US drone strike in Baghdad. Soleimani spent long periods of time on the ground with allied fighters in Iraq and Syria and was widely regarded as one of the most powerful figures in the region.

His replacement, General Ismail Qaani, has failed to gain the same prominence, and Israel has launched a series of successful raids in recent months targeting IRGC officials in Syria.

Former Hezbollah leader Hassan Nasrallah assumed some coordination duties after Soleimani’s death, setting up an operations room in Lebanon to help oversee the alliance. But it is unclear what happened to those efforts after he was killed by Israel in September.

As Hezbollah and Iraqi militias return to Syria, they say their primary mission is to maintain Iran’s “axis of resistance.” However, they also characterize their struggle as defensive.

The Hezbollah commander said his forces “prefer to fight the enemy in another country, rather than on our land.”

And Kadhim al-Fartousi, a spokesman for another Iraqi militia, Kataib Sayyid al-Suhanda, said he feared “Iraq will be the first country to suffer” if Assad is toppled by rebel forces.

“If we feel that Syria is ready to fall, we will not remain spectators,” he said.

Mustafa Salim is a reporter in the Washington Post’s Baghdad bureau. He joined the paper in 2014, covering the rise of Islamic State and Iraq’s military campaign against it.