When Hezbollah started fighting on behalf of President Bashar Al Assad at the onset of the Syrian civil war in 2011, the Iran-backed Shiite group sought to keep a low profile while regular forces flew the national flag and took credit for capturing rebel areas. Covertly, the group had long been given free access to the port of Latakia, rebuilding its military inventory in the wake of the 2006 war with Israel.

This maritime supply line, now dubbed the Syrian express, was complemented by an overland route that allowed their weapons stockpile in Lebanon to swell from perhaps 15,000 rockets in 2006 to as many as 150,000. Heavy weapons, including lethal Konkurs anti-tank missiles – recently captured in large numbers by the Israelis in south Lebanon – also came via the Syrian military from Russian manufacturers.

These now form part of the infantry arsenal that is vital for the group's strength in southern Lebanon. There, they are powerful and influential. Hezbollah has given Iran an arc of control extending from Baghdad to Beirut. Its presence in Syria, now challenged by an Israeli air campaign, is crucial to enforcing the Iranian influence in the country and maintaining military supplies and strategic depth in Lebanon, where Hezbollah has been fighting Israel in a ground war since October.

But the civil war in majority-Sunni Syria moved Hezbollah out of the shadows. In the central city of Al Qusayr near the Lebanese border, Shiite flags with the inscription “Oh Hussein” went up on several mosques after Hezbollah defeated Sunni rebels in 2013.

It was a major military clash that publicly showcased how involved the militant Shiite group had become, a fact praised by its late secretary general Hassan Nasrallah. “Qusayr is so strategic that Hezbollah did not hide its intention to make it its bastion in Syria,” said a retired officer who lives in the city.

Israel responded to Hezbollah’s growing presence almost immediately, having already bombed a convoy of missiles being transported by the group’s Unit 4400 in January 2013. The unit runs their Syrian supply line.

More than a decade after Hezbollah established supremacy in Al Qusayr and the surrounding countryside, the area has become a prime target of an Israeli air campaign that has intensified in the last three months.

Gone are the days when strikes were occasional and unannounced by Israel. Even the peak of the bombing, which Israel called “the war between the wars”, reaching 200 strikes in 2017, is small compared to Israel’s daily air strikes currently hitting Lebanon and Syria.

In Syria, it is aimed at undermining military infrastructure and supply lines crucial to the survival of Hezbollah. Increasingly, it targets a wide array of Iran-backed Iraqi militias, who now operate under the banner of the Islamic Resistance and hold sway in Abu Kamal on the border with Iraq, and other towns in Deir Ezzor governorate, folding in members of powerful Iraqi militias such as Kataib Hezbollah. Where once the focus of bombing was Hezbollah and occasionally the Syrian regime when it fired on Israeli jets, strikes now occur the length and breadth of regime-held areas.

The strikes, however, have not altered the frontiers of the civil war. Israel’s campaign has not been aimed at annihilating Syrian army units and allied militia formations, stationed at fault lines with Turkish proxies in the north, near Kurdish-dominated proxies of the US in the east.

Over the last year, Israeli attacks have killed hundreds of Hezbollah commanders, striking weapons and communications specialists, according to security sources in the region and abroad. Air strikes are supplemented by methods that have long been the hallmarks of pro-Iranian militias, such as car bombs and booby traps.

The more Hezbollah’s military expertise is sapped, the more shaken Iran’s longtime strategy of relying on proxy warfare in the region becomes. It is also eroding the capability of groups who have regularly attacked the roughly 900 US forces in eastern Syria. Also at stake for Tehran is an ideological, politico-military control model it developed for its non-state allies, which expanded in the region in the wake of the US invasion of Iraq.

“Israel’s aim is the decapitation of Hezbollah,” said a senior western military intelligence official, who had predicted that Israel would launch the current campaign after years of eavesdropping on Hezbollah’s communications as well as the Syrian military network, despite their military communications undergoing upgrades by Iran in the last decade. He said that the Israeli military risks a “bloody nose if it pursues Hezbollah on the ground deep in the interior of the Levant, but Israel appears so far satisfied with conducting the war mainly from the air".

Lebanese political commentator Sarkis Kasarjian said that intensifying Israeli attacks on Hezbollah and its allies in Syria aim to consolidate war gains in Lebanon and Gaza. The lack of an Iranian response has bolstered Israeli confidence that it can achieve this goal, Mr Kasarjian said.

Syria powerless

The Syrian military, lacking air defence capabilities, also “does not have many options” to deter Israel, which could emerge as the "biggest winner” if it continues undermining Iran’s logistics through Syria. Iran has recently insisted that whatever happens, it will not reduce its presence of small numbers of Islamic Revolutionary Guard Corps-Quds Force advisers in Syria.

Two senior IRGC generals were killed in a strike on Iran's Damascus consulate in April, dragging Israel and Iran into direct exchanges of missiles and air strikes. Under relentless and unanswered Israeli strikes, the Syrian regime appears on the verge of becoming “the biggest loser”, said Mr Kasarjian.

Nonetheless, the way Hezbollah has entrenched itself in Al Qusayr and other supply hubs illustrates limits to the Israeli campaign. A main east-west corridor runs from Abu Kamal on the Iraqi border, passing through Palmyra, the target of a heavy Israeli attack this week, to Qusayr and the Qalamoun mountains overlooking Lebanon to the south, according to Syrian military defectors and Arab and European intelligence officials.

Another main north-south line runs from an Iranian-controlled military compound in the Sfeira district on the outskirts of Aleppo and other areas in the countryside near the city to Al Qusayr. It also connects Al Qusayr with two weapons-development and assembly facilities in the province of Hama: Jabal Taqsis and Masyaf, which was the target of a rare Israeli ground raid in September, an intensification of the Israeli campaign.

According to residents and intelligence sources, Hezbollah controls everything, from who is allowed into the town and the surrounding countryside, to the roads and facilities of Syria’s own military. The Syrian officer, who fought in an infantry division in the civil war, said he was not allowed to go back to a farm he owns in Al Qusayr when he retired three years ago.

He found out he was persona non grata in his hometown from checkpoints controlled by the Hajrs, a Shiite family that became one of the auxiliaries that Hezbollah used to secure the outer perimeter of Al Qusayr. As with these auxiliaries, Hezbollah has long played the role of training, strengthening and in some cases leading units of Syrians, Iraqi militias and other forces in the irregular mix of pro-regime forces.

The hodgepodge of groups has also included Afghan Shiites in the Fatimeyoun brigade. “Although I fought with them, they did not trust me,” said the officer, who did not want to be named.

He returned to Al Qusayr at the onset of the Hezbollah-Israel war in October, having secured help from a contact at Syrian Military Intelligence, who convinced Hezbollah that he was not a threat. Syrian Military Intelligence is headed by Brig Gen Maher Al Assad, who is widely regarded as Iran’s main Syrian facilitator in the country.

Relentless Israeli strikes

Reconnaissance data compiled by an opposition military cell shows that Israel has carried out 13 air raids on roads connecting Al Qusayr with Lebanon in the last month alone, and four raids on weapons storage facilities in the area. Israeli drones have struck at least two vehicles carrying Hezbollah-linked militiamen and destroyed a Syrian security building at the Jayousieh border crossing with Lebanon.

Such movements are easily spotted by the Israelis, and all it takes is lax communication from Hezbollah and its allies to reveal locations. The National previously reported how the group had used weakly encrypted radios since 2022. Airborne devices called IMSI catchers can be placed on drones to locate mobile phone calls, while the same drones can – according to one Israeli defence company – track targets over 13 square kilometres from 15,000 feet.

A former military telecoms specialist who was employed by the Syrian military said that Israel had also penetrated the Soviet-era radios and Malaysia-manufactured walkie-talkies and other communication devices used by the army, as well as spying on their military fibre optic network and destroying a large part of a mobile communications system Iran started installing in 2012. “They broke through the encryption years ago,” he said.

At the same time, Israel has intensified its campaign on Syrian air defences, particularly in the south of the country, where drones were launched at Israeli forces in the Golan Heights. One raid last month on the Khalkhala military airport in Deraa destroyed its radar system, opposition data showed.

Another position east of the airport, manned by the 15th Special Forces Division and Hezbollah, was also hit. The site, equipped with infrared cameras for night vision, is tasked with protecting the airport.

One more mobile radar system at Thula, another military airport in Deraa, was also destroyed after a failed attempt by anti-aircraft batteries to repel the attack. An electronic warfare and radar site near the town of Al Kafr in Sweida province was also attacked in October.

Despite so many strikes, Bilal Saab, a former US government official who is now the head of the US-Middle East Practice with Trends, a regional consultancy, said the long-term outcome is not clear. Israel’s air campaign “was always going to be limited because the supply routes are diverse and require constant Israeli oversight, which Israel doesn’t have or see as a top priority”, he said.

“The air campaign is meant to degrade and deter, not defeat. It can’t defeat without a full-fledged military presence on the ground, which I’m not sure is in the cards.”

Axis of Resistance

One figure recently said to have been targeted by Israel epitomises the long role of Hezbollah and Iran’s proxies in Syria, Lebanon, Yemen and Iraq, known as the Axis of Resistance. Ali Musa Daqduq – whose reported death in early November has not been confirmed – was an elite member of the organisation captured in Iraq by British special forces in 2007 and released by Iraq in 2011 following an exchange with a British civilian hostage.

His interrogation revealed his key role co-ordinating with Asaib Ahl Al Haq, an Iraqi militia under the government-linked, Iran-backed Popular Mobilisation Forces. Mr Daqduq was their main liaison in Iraq, helping them plan deadly attacks against Americans.

When the US left, he went on to play a key role in the Syrian civil war, where Asaib quickly sent fighters for training within Syria. Now militias – possibly including members of Asaib under the banner of the Islamic Resistance – have led a campaign attacking US forces in eastern Syria, often drawing retaliatory strikes. Hezbollah confirmed that Mr Daqduq's son, Hassan, who was serving in the organisation, had been killed in an air strike in December.