• Israel has launched hundreds of airstrikes on Syria since Bashar Assad's ouster.
• Its forces have also advanced into the Golan Heights, a previously demilitarized zone in southwestern Syria.
• Israel's defense minister said it intended to create a "defense zone free of weapons and terrorist threats in southern Syria."

Israel says it has launched hundreds of airstrikes on Syria in the days since Bashar Assad's regime collapsed.

On Tuesday, the Israel Defense Forces said it had "struck most of the strategic weapons stockpiles in Syria" in 48 hours as part of a push to stop the weapons "falling into the hands of terrorist elements."

Israeli Prime Minister Benjamin Netanyahu on Sunday welcomed the toppling of Assad but said the moment is "fraught with significant dangers."

Assad's downfall followed a surprise rebel offensive led by the Islamist opposition group Hayat Tahrir al-Sham, which traces its roots to Al-Qaeda.

Per Tuesday's IDF statement, the Israeli military had conducted strikes on targets including antiaircraft batteries, Syrian Air Force airfields, and weapons production sites.

It said the strikes took out "numerous" strategic assets, including cruise and Scud missiles, tanks, radars, and attack helicopters.

The UK-based Syrian Observatory for Human Rights, which gathers data from on-the-ground sources in Syria, said on Tuesday that it had documented nearly 310 Israeli airstrikes on Syrian territory since Assad's government collapsed on December 8.

The Israeli navy also hit two ports, one in Al-Bayda and one in Latakia, the IDF said.

The IDF did not say how many ships were struck, but Israeli Defense Minister Israel Katz said that the mission had been a "great success" and that the navy had destroyed the Syrian fleet overnight, CNN reported.

The IDF declined to clarify what proportion of Syria's military capability had been taken out when approached by Business Insider for comment.

Katz said that Israel intended to create a "sterile defense zone free of weapons and terrorist threats in southern Syria," adding that it's "in order to prevent terrorism in Syria from taking root," per The Guardian's translation.

The US and Turkey have also been reported to be carrying out airstrikes in Syria since Assad's fall.

Washington has targeted ISIS camps and operatives in Syria with precision strikes, President Joe Biden said on Sunday.

Jonathan Lord, a former political-military analyst at the Pentagon, previously told Business Insider the US military was hitting as many targets as possible as it was "rightly worried that ISIS could slip through the cracks in the chaos."

For its part, Ankara has reportedly launched a drone strike on a military site in an area held by the Kurdish-led Syrian Democratic Force, which it views as a terror group.

Troops on the ground

The strikes come as Netanyahu announced that he had sent forces into the Golan Heights, a formerly demilitarized buffer zone in southwestern Syria.

In a video address on Sunday, Netanyahu described this as a "temporary defensive position" designed "to ensure that no hostile force embeds itself right next to the border of Israel."

Israel has denied reports that its forces have advanced beyond the buffer zone.

An anonymous Syrian source previously told Reuters that troops had reached Qatana, a town close to the Syrian capital Damascus.

Business Insider could not independently confirm the report. The IDF declined to comment.

Several Arab countries have criticized the move into the Golan Heights.

Egypt's foreign ministry said on Monday that it constituted "an exploitation of the state of fluidity and vacuum in Syria to occupy more Syrian territories," the Egypt Independent reported.

The Arab League said that Israel was "taking advantage of the developments in the internal situation in Syria," per CNN.

Stéphane Dujarric, a spokesperson for the UN Secretary-General, confirmed at a press briefing on Monday that the Israeli military had entered the Golan Heights and was stationed in at least three locations there.

Dujarric said that peacekeepers at the United Nations Disengagement Observer Force had told Israel that such actions would violate the 1974 disengagement agreement and that there should be no military forces or activities in the area.

Netanyahu said that the agreement had "collapsed" and that "the Syrian army abandoned its positions."

• Ukraine sent drones and drone operators to Syrian rebel forces, The Washington Post reported.
• Groups led by Hayat Tahrir al-Sham overthrew Bashar Assad's decades-old rule on Sunday.
• The Ukrainian aid played a modest role in toppling him, Western intel sources told the outlet.

Ukrainian intelligence supplied Syrian rebels with about 150 drones and 20 drone operators last month, shortly before the offensive that toppled Syrian dictator Bashar Assad last week, The Washington Post reported, citing sources familiar with Ukrainian military activities.

Ukraine's aid was sent four to five weeks ago by Ukrainian intelligence operatives as part of efforts to weaken Russia and its Syrian allies in the region, sources familiar with Ukraine's operations abroad told the Post.

Business Insider was unable to independently verify the report.

The military aid played a modest role in ousting Assad, Western intelligence sources told the outlet.

On Sunday, Syrian rebels led by the Islamist group Hayat Tahrir al-Sham overthrew Assad after a lightning two-week campaign that caught the world off guard and ended Assad's 24-year rule.

The Post's report would be in keeping with Ukraine's efforts to undermine Russia's influence abroad.

Earlier this year, The Kyiv Post published videos that it said showed Ukrainian special forces interrogating Russian mercenaries in Sudan, and special forces fighting side by side with Syrian rebels against Russian mercenaries and Assad's forces.

A source within Ukraine's military intelligence agency told the outlet in June that since the start of the year, Ukrainian operatives had supported Syrian rebels in inflicting "numerous" strikes on Russian military facilities in the region.

In September, the Syrian newspaper Al-Watan reported comments from Russian Foreign Minister Sergey Lavrov, who said Ukrainian intelligence emissaries in Idlib, in Syria's northwest, were conducting "new dirty operations" and recruiting rebel fighters there.

Last month, Alexander Lavrentyev, Russia's special envoy to Syria, told Russian state news agency TASS that Ukraine's Main Directorate of Intelligence was arming "terrorists" in Idlib and that Ukrainian specialists were present there.

Ukraine's intelligence services didn't immediately respond to requests for comment from BI.

Alexander Libman, a professor of Russian and East European politics at the Free University of Berlin, told BI that if Ukraine is confirmed to have sent drones and drone operators to Syria, it would be surprising given how "problematic" the situation is in eastern Ukraine.

"I am not sure Ukraine can gain a lot by engaging in these types of operations," Libman said. "Rather, it will simply waste resources it needs to fight the war on Ukrainian soil itself."

The collapse of Assad, however, could jeopardize Russia's military footprint in Syria, where it could lose control over the Hmeimim air base and the Tartus naval base.

Russia has used those bases to project power in the Mediterranean and into Africa, and as a counter to NATO's southern flank.

Satellite images taken earlier this week by Maxar Technologies, obtained by BI, show Russian aircraft still present at Hmeimim, but Russian warships no longer present at Tartus.

• Russia hasn't mass-evacuated troops and gear out of its key bases in Syria.
• A senior analyst said the signs would be clear — such a retreat would be difficult to hide.
• Russia said it's trying to work out a deal for its bases with the new Syrian government.

The Russian military is still stationed at its Syrian bases after the fall of Bashar Assad's government, and analysts say an evacuation will be easy to spot.

The Kremlin has two major facilities in the country that were hosted by Assad — the Tartus naval base and the Khmeimim air base — which are crucial to Russian access to the Mediterranean and Africa.

According to Russian state media, rebel forces now control the Latakia province, where these bases are located.

With Moscow's long-term access to those bases now under question, satellite images show that its warships have vacated Tartus since Monday. Several were spotted holding positions about 15 km from the coast.

It's unclear if these vessels will return.

But satellite images also show that a full evacuation of Tartus hasn't happened, Dara Massicot, a senior fellow at the Carnegie Endowment for International Peace, told the Financial Times.

"And if they have to leave Tartus, you'd actually see more ships show up to help move things out," she told the outlet.

It's possible that Russia moved its ships temporarily out to sea to protect them while conditions in Syria remain uncertain.

At Khmeimim, which Russia uses as its primary channel for flying troops into Africa, satellite images this week showed that much of the Kremlin's equipment, including fighter jets and helicopters, remained on-site.

Massicot wrote in a thread on X that an evacuation of the airbase "will be obvious."

"An air evacuation would take hundreds of sorties of IL-76 and An-124, not the handful identified yesterday at Khmeimim," she wrote, referring to several Ilyushin and Antonov freight airliners spotted at Khmeimim earlier this week.

"When Russian forces deployed to Syria in 2015, they flew almost 300 sorties in two weeks, and that was before base expansion," Massicot added.

Analysts from the Institute for the Study of War, a Washington-based think tank, wrote that Russia is likely delaying a total evacuation as it tries to suss out a deal with a new Syrian government.

They said Russia is still maintaining its assets in Khmeimim, and that a "lack of a coherent Russian response" indicates Moscow is still watching the situation.

"The Kremlin is very likely hesitant to completely evacuate all military assets from Syria in the event that it can establish a relationship with Syrian opposition forces and the transitional government and continue to ensure the security of its basing and personnel in Syria," the analysts wrote.

The Kremlin hopes it won't have to evacuate

Russia is also publicly signaling that it isn't giving up on its vital bases.

Dmitry Peskov, a Kremlin spokesperson, told reporters that Russia has been in contact with "those capable of ensuring the security of military bases."

Meanwhile, Russian state media outlet TASS cited an unnamed source in the Kremlin saying that Syrian opposition leaders had guaranteed the safety of Tartus and Khmeimim.

On the other hand, Ukraine's intelligence division said on Tuesday that Russia has a plan to evacuate Khmeimim with Antonovs and Ilyushins, and that Russian troops have begun dismantling equipment at Tartus under the supervision of special forces. It did not say how it sourced this information.

Russia's future in Syria unclear

Despite those forecasts, it's unclear how a post-Assad Syria will take shape. Rebel forces in the country were largely splintered, consisting of various separate factions sharing the common cause of toppling Assad.

Mohammed al-Bashir, who ran rebel-held pockets of northern Syria, said on Tuesday that he had been named interim prime minister.

The Islamist group at the helm of the rebel victory, Hayat Tahrir Al-Sham, is led by Abu Mohammad al-Jolani, a former Al Qaeda-affiliated fighter who's said to have cut ties with the terrorist organization.

But he is still listed as a terrorist by the US, with a $10 million bounty on his head. Though he has been a prominent contender for leadership, he has not taken an official leadership position as of press time.

• The downfall of Assad has threatened Russia's military presence in Syria along with its wider strategic objectives.
• Russia's bases in Syria made it a major diplomatic player in the Middle East.
• The bases were also crucial for its activities in Africa.

The fall of Bashar Assad has thrown Russia's military presence in Syria into question. It also poses a threat to Russia's ability to project power throughout the Middle East and beyond.

On Sunday, Syrian rebels, led by the Islamist group Hayat Tahrir Al-Sham, overthrew Syria's longtime autocratic ruler.

It followed a dizzying two-week campaign that caught the world off guard and many are now trying to work out what will come next for the country.

Russia has been a close ally of Syria and has leases on two military bases in the country, giving it a strategic foothold in the Middle East.

"It hits them hard," Edmund Fitton-Brown, a senior advisor to the Counter Extremism Project, said of Russia.

He added: "Syria has been their most reliable Arab ally."

A springboard to power

In 2017, Syria granted Russia a 49-year lease on the Hmeimim air base and the Tartus naval base, in return for military assistance.

Russia has used the bases to project power in the Mediterranean and into Africa, and as a counter to NATO's southern flank.

"These bases are the most important bases outside the direct sphere of Russian influence," Andreas Krieg, a Gulf specialist at the Institute of Middle Eastern Studies at King's College London, told Business Insider.

Ann Marie Dailey, a geopolitical strategist at RAND, told BI that despite its massive landmass, Russia "doesn't have great geography for power projection."

"It doesn't have warm water ports that have direct access to the oceans," she added. "And so having a port in the Mediterranean is incredibly strategically useful."

Hmeimim, meanwhile, gives Russia a refueling base and overflight access throughout the Middle East and on to Africa, she said.

On Sunday, Ukrainian military intelligence said that Russia had pulled two ships from Tartus, and had transferred weapons from Hmeimim.

BI was unable to independently verify the report.

But satellite images captured by Planet Labs PBC show Russian warships that had been seen in Tartus earlier this month were gone as of Monday.

Kremlin spokesperson Dmitry Peskov said Russia intended to have serious discussions with future Syrian authorities about access to the bases, but that it is too soon for now.

The potential loss of influence in Syria is not just about state power. The bases have also allowed support for the activities of the Russian paramilitary group Wagner.

"If you look at the Wagner footprint in Africa, you can tell that it's been enabled by the fact that they have that access in Syria to support those operations," said Dailey.

According to the Institute for the Study of War, losing the bases in Syria will "immediately" interrupt Wagner's rotation and resupply efforts.

Russia's ambitions for global leadership

Russia's involvement in Syria is a legacy of the Soviet era when the USSR traditionally maintained strong ties with other socialist states.

Russia propped up the Assad regime for more than a decade, notably sending aid during the 2011 Arab Spring, and troops and weapons to help counter the uprising in 2015.

Russian President Vladimir Putin had many reasons to stick his neck out for Assad.

"By backing Assad, Russia positioned itself as an indispensable player in regional politics, thereby increasing its diplomatic leverage," said Ali Bilgic, a professor in international relations and Middle East politics at the UK's Loughborough University.

But the huge cost of invading Ukraine appears to have forced Russia to choose between the two.

It "really speaks to how stretched thin Russian forces are," according to Dailey.

Putin has based Russia's international stature on the idea it can play a major role in different parts of the world, said Cristian Nitoiu, a Russia-focused lecturer in diplomacy and foreign affairs, also at Loughborough University.

Yet Putin's refusal to help Assad this time "basically shows that Russia was unable to support one of its long-lasting friends," Nitoiu said.

"The events in Syria can be seen as a sort of strategic failure on the part of Russia, and the optics look really bad," he added.

An uncertain future

In a statement on Sunday, Russia's foreign ministry said it was maintaining contact with "all" Syrian opposition groups, adding that while Russia's Syrian bases are on high alert, there's no serious threat to their security at the moment.

Russia has called Hayat Tahrir Al-Sham a terror group — so the fact that they are communicating with rebel groups now "demonstrates the importance of these bases," Dailey said.

HTS is also designated a terror group by the US and the UN.

What the US does regarding events in Syria will also be pivotal to what sort of foothold Russia can maintain, Loughborough University's Bilgic said.

On Saturday, President-elect Donald Trump posted on Truth Social: "THIS IS NOT OUR FIGHT. LET IT PLAY OUT. DO NOT GET INVOLVED!"

Should the US withdraw all involvement, Russia could exploit any ensuing power vacuum. But "this scenario appears improbable," Bilgic said.

In fact, diminishing Russian influence in Syria is a huge strategic draw for the US, he said, adding that there is also a concern that a new Russia-backed government could give room to ISIS, as well as threats to Israeli security.

Russia's presence in Syria has also helped it shape its objectives in energy markets, Bilgic said.

"Economically, the Tartus base played a role in Russia's energy strategy, helping to counter competing projects like the Qatar-Turkey pipeline," he said.

A grim reminder

What has happened in Syria in recent days may lead to some sleepless nights in Russia.

"I think it will rattle some folks in the Kremlin to see just how quickly Russia's military had to withdraw," Dailey said.

Assad's fall may also be a grim reminder for those in power in Russia of the necessity of crushing domestic resistance quickly, she said.

"Anyone in the Kremlin, because they've studied Russian history, knows that an autocratic regime can crumble very quickly."

• Western leaders have welcomed the fall of Bashar Assad but warned of uncertainty about what's next.
• Biden warned of "a moment of risk" over Syria's future.
• Assad was ousted by a coalition that included Hayat Tahrir al-Sham, whose leader fought the US in Iraq.

World leaders are warning the downfall of Syria's dictator Bashar Assad leaves the country's future uncertain, as most of them celebrate his toppling.

Assad had, for more than a decade, faced a loose coalition of rebel groups, including the US-backed Syrian Democratic Forces. But it was Hayat Tahrir al-Sham, an Islamist group that traces its roots to Al Qaeda, that stormed from city to city in days, prompting Assad to flee to Russia, which had helped keep him in power.

Questions remain about what sort of government may form under Hayat Tahrir al-Sham's leader, Abu Mohammad al-Jolani. Though he has broken ties with Al Qaeda and is projecting messages of religious tolerance, the US designates him a terrorist and has a $10 million bounty on his head.

Here's how the world's been reacting to Assad's fall.

US: President Joe Biden

"At long last, the Assad regime has fallen," Biden said on Sunday during a press briefing in the Roosevelt Room.

Biden called the Assad government's expulsion a "fundamental act of justice" and a "moment of opportunity for the long-suffering people of Syria to build a better future for their proud country."

"It's also a moment of risk and uncertainty," the president added. "As we all turn to the question of what comes next."

The US has been conducting airstrikes against ISIS targets in Syria, Biden said.

US: President-Elect Donald Trump

Trump, who is to succeed Biden on January 20, referenced the war in Ukraine as a key reason for Russia's waning military support for Assad.

"Assad is gone. He has fled his country. His protector, Russia, Russia, Russia, led by Vladimir Putin, was not interested in protecting him any longer," he wrote on Truth Social on Sunday.

In a post on Saturday, Trump wrote that the US should avoid any involvement in Syria.

"THIS IS NOT OUR FIGHT. LET IT PLAY OUT. DO NOT GET INVOLVED!" he wrote.

EU: European Commission President Ursula Von der Leyen

In a statement on Sunday, Von der Leyen wrote that Europe hoped to support Damascus in "rebuilding a Syrian state that protects all minorities."

"This historic change in the region offers opportunities but is not without risks," Von der Leyen wrote.

The majority of the nation's population is Sunni Muslim, but among them are Alawites, Christians, Shiite Muslims, Druze, and other ethnicities and religious movements.

UK: Prime Minister Keir Starmer

Starmer cautioned on Sunday that Syria's new political situation is still in its "early days," but said Assad's fall was a "very good thing for the Syrian people."

"The Syrian people have suffered under Assad's barbaric regime for too long and we welcome his departure," Starmer said. "Our focus is now on ensuring a political solution prevails, and peace and stability is restored."

Starmer called for a "rejection of terrorism and violence" and for civilians to be protected.

Germany: Chancellor Olaf Scholz

Scholz posted identical statements on Sunday in German, Arabic, and English.

"Today, we stand with all Syrians who are full of hope for a free, just, and safe Syria," the chancellor said.

"A political solution to the conflict in Syria is possible. With international partners and on the basis of the resolutions of the UN Security Council, Germany will make its contribution," he added.

A few hours earlier, Scholz said that the end of Assad's rule was "good news." He also urged that civilians and minorities be protected.

France: President Emmanuel Macron

"The barbaric state has fallen. At last," Macron said in identical statements in Arabic, French, and English.

He called the current situation a "moment of uncertainty" and said he wished Syrians "peace, freedom, and unity."

"France will remain committed to the security of all in the Middle East," Macron added.

Canada: Prime Minister Justin Trudeau

Trudeau also celebrated Assad's fall as the end of decades of dictatorship in Syria, and said Canada was "monitoring this transition closely."

"A new chapter for Syria can begin here — one free of terrorism and suffering for the Syrian people," he said.

China: Foreign Ministry

The Chinese foreign ministry's initial response focused on the status of its citizens in Syria.

A ministry spokesperson said on Sunday that China's embassy in Syria was still operational and was assisting Chinese nationals in the country.

"We urge relevant parties in Syria to ensure the safety and security of the Chinese institutions and personnel in Syria," they added.

On Monday, a spokesperson for the foreign ministry, Mao Ning, said Beijing was "closely watching developments."

"We hope all relevant parties will proceed on the basis of the Syrian people's fundamental interests and find a political resolution as soon as possible to restore stability in the country," she said.

Iran: Foreign Ministry

Iran, which backed Assad for over a decade, indicated that it hopes to continue to establish a presence in the region.

"The Islamic Republic of Iran, emphasizing Syria's role as an important and influential country in West Asia, will spare no effort to help establish security and stability in Syria," its foreign ministry said in a statement.

Despite its past support for Assad, it added that "determining Syria's future and making decisions about its destiny are solely the responsibility of the Syrian people, without any destructive interference or external imposition."

Turkey: Foreign Minister Hakan Fidan

Fidan said Assad's fall paves the way for millions of Syrian refugees in neighboring Turkey to potentially return home.

"As of this morning, the Syrian people have started a new day in which they will determine the future of their country," Fidan said in a statement.

Turkey is home to some 3.6 million Syrian refugees, and Ankara has been actively supporting some rebel forces in the north with troops, drone strikes, and artillery.

Fidan added that Turkey would "assume responsibility for whatever needs to be done to heal Syria's wounds and ensure its unity, integrity, and security."

Russia: Foreign Ministry

In a statement on Sunday, Russia's foreign ministry said it was monitoring Syria "with extreme concern."

The ministry said Assad had resigned after discussing with "a number of participants" in the civil war, and that Moscow was not involved in the negotiations.

"However, we call on all the parties involved to renounce the use of violence and resolve all governance issues through political efforts," it said.

"In this regard, the Russian Federation maintains contact with all Syrian opposition groups," the ministry added.

Russia has said for years that it's supported Assad to protect Syria's legitimacy and to fight terrorism.

It fields two major military bases in Syria, the Hmeimim Air Base and the Tartus Naval Base, which provide Russia with access to Africa and the Mediterranean.

"Russian military bases in Syria are on high alert. There is no serious threat to their security at the moment," the foreign ministry said.

This is a developing story. Please check back for updates.

• Syria's embattled president is losing ground to advancing rebels after years of stalemate.
• In the past, Iran orchestrated the interventions that stopped the opposition forces' momentum.
• "I'm not sure Iran can muster the numbers in time to turn this situation around," an analyst said.

Since the early stages of Syria's bloody civil war that began in 2011, Iran has supported Syria's strongman president, Bashar Assad. Now with the loss of Syria's second city, Aleppo, to Assad's opponents, Tehran has vowed to continue this support — but it almost certainly has less to offer than a decade ago.

Syrian rebel forces spearheaded by the Islamist Hayat Tahrir al-Sham militant group seized Aleppo in a shock offensive last week, surprising the world and returning the Syrian conflict to the headlines for the first time in years. The rebels did not stop there. Advancing in the face of Russian and Syrian airstrikes, they overran Syria's fourth-largest city, Hama, on Thursday.

"The Syrian government has lost a lot of terrain, including the city of Aleppo. You can't really overstate the seriousness of that," Aron Lund, a fellow with Century International and a Middle East analyst at the Swedish Defence Research Agency, told Business Insider. "Aleppo is a huge city, a really large urban area that will be difficult to retake once lost if Assad is unable to move on it before the insurgents dig in."

Earlier in the Syrian conflict, Iran helped orchestrate interventions on Assad's side by its powerful Lebanese proxy Hezbollah in 2013, and Russia in 2015.

These decisive interventions helped him turn the tide, culminating in a ferocious, scorched-earth campaign against opposition groups in east Aleppo in 2016.

The latest offensive has prompted some outside intervention. Hundreds of Iran-backed militiamen in Iraq are entering Syria. Russia has carried out airstrikes to impede the opposition's advance. However, these are small-scale compared to past interventions. And Hezbollah isn't intervening for now.

"I'm not sure Iran can muster the numbers in time to turn this situation around," Lund said. "Hezbollah, which was Tehran's primary instrument in Syria over the past decade, is now stuck in Lebanon, tending to its wounds and trying to get back on its feet after being mauled by Israel over the course of a two-month war."

Hezbollah is estimated to have upwards of 100,000 fighters and a vast missile arsenal, but those have been battered by Israel's airstrikes and occupation of southern Lebanon.

"The Lebanon ceasefire is really brittle, and as long as conflict could re-erupt at any moment, I don't think Hezbollah has the manpower to spare," Lund said. "Even if they're able to send some men Assad's way, I doubt it would be a game-changing number."

Iran's other options are mobilizing more Iraqi militias or sending personnel from its own Islamic Revolutionary Guard Corps paramilitary or its regular army.

"It's possible that Iran will try to send more arms and ammunition," Barbara Slavin, a distinguished fellow at the Stimson Center in Washington and founder and former director of the Future of Iran Initiative at the Atlantic Council, told BI.

"It is also probably counting on Russian airstrikes to stall the HTS offensive and it is clearly having back-channel talks with Turkey," Slavin said. "The Turks may be angling to get Iran to turn a blind eye to new attacks on the Kurds in return for urging HTS to hit pause."

HTS is not a Turkish-controlled proxy like the self-styled Syrian National Army coalition of opposition militias that is also advancing across Aleppo province. However, Turkey has closely coordinated its army's deployment in Syria's Idlib with HTS, which has been the predominant power in that northwestern Syrian province for years now.

"Iran is also looking to cultivate a relationship with Trump, which further limits its freedom of maneuver in the region," Slavin said.

"Iran is in a terrible situation currently without the necessary military, economic, and political capacity to spare," Arash Azizi, senior lecturer in history and political science at Clemson University, told BI.

"Its myriad of problems includes the fact that many Iraqis are reluctant to get involved in a renewed war in Syria."

While Iran will undoubtedly remain committed to supporting Assad, it's unlikely to prove capable of organizing a 2016-style counteroffensive to recapture Aleppo.

"That would require a lot of planning and a lot of diplomatic bargaining with Turkey and other powers," Azizi said.

Century's Lund recalled that the last time Iran intervened to help Assad recapture Aleppo, it did so in close collaboration with Russia.

"If they're going to replicate that success now, the Russians would probably need to bring the air component," Lund said. "Iran has no air force to speak of and if Iranian jets were to show up in Syria, Israel would go after them immediately."

Russian jets and air defenses afford Iran some protection since Israel is more hesitant to clash with Russian forces than they are with Syrian or Iranian ones.

But it remains to be seen how much airpower Russia can spare with its fighters and bombers engaged in the invasion of Ukraine.

"It's worth noting that the Syrian conflict is so small-scale compared to Ukraine that even a relatively small contribution of assets could have an impact there," Lund said.

The Iraqi militiamen entering Syria are more likely to serve as a holding force to help Assad avoid losing more territory.

"Assad needs to hold onto the capital and its immediate environs if he has a chance to survive as Syrian leader," Stimson's Slavin said.

Since Syria doesn't have a sizable Shia minority like Lebanon, Iran has been unable to stand up a local proxy as effective or powerful as Hezbollah in neighboring Lebanon.

Any efforts Iran may take to help Assad coincide with its own priorities to seek an acceptable deal with President-elect Donald Trump's incoming administration. "Iran also wants to at least try for a deal with Trump, so a more aggressive regional posture will not work as regional issues will be on the table this time along with the nuclear file," Slavin said.

As this crisis unfolds, it's striking how "unimportant and absent" the US has been, Azizi noted.

"The US has forces on the ground and also airpower that it has used to attack certain forces on Syrian territory," Azizi said. "But it's clearly not a main player and doesn't seem to have a clear, strategic goal or any particular focus on Syria."

And it remains unclear what President-elect Trump will do about Syria upon reentering office in January.

"As with most other matters, President Trump remains unpredictable," Azizi said.

Paul Iddon is a freelance journalist and columnist who writes about Middle East developments, military affairs, politics, and history. His articles have appeared in a variety of publications focused on the region.