BEIRUT (Reuters) - The vehicle carrying Iranian Brigadier General Hossein Hamedani was passing through the outskirts of Aleppo on the afternoon of Oct. 8 when it was shot up by Islamic State fighters.

Members of Iran's Revolutionary Guards hold pictures of their Brigadier General Hossein Hamedani during his funeral in Tehran, Iran in this October 11, 2015 file photo. REUTERS/Raheb Homavandi/TIMA/Files

Hamedani was hit in the left eye by a bullet and died after the driver lost control of the vehicle. He was the most senior Revolutionary Guard commander to be killed in Syria to date and also one of a growing number of Iranian military personnel to lose their lives there.

The death of Hamedani, who played a vital role in Iranian military efforts in Syria, was described by a representative of Supreme Leader Ayatollah Ali Khamenei in the Revolutionary Guards and published by the Entekhab news site in mid-October.

It was an event that marked the start of a new development in Iran’s military involvement in Syria, where experts believe Tehran may have as many as 3,000 troops.

Since early October, nearly 100 Revolutionary Guard fighters or military advisers, including at least four senior commanders, have been killed there, according to a tally from Iranian websites.

That is only slightly less than half of all the casualties suffered by the Guard in Syria since the beginning of 2012, when death notices began to appear.

Syria’s war has drawn in diverse powers: Iran has allied with Russia in supporting president Bashar al-Assad while Saudi Arabia, Turkey and Qatar have been backing the opposition.

The United States, France and Britain have been carrying out attacks in Syria primarily targeting Islamic State, which controls broad swathes of territory in both Syria and Iraq.

The conflict has heightened sectarian tension across the region as Iran has rallied Shi’ite fighters from Iraq, Lebanon, Afghanistan and Pakistan to fight a mostly Sunni opposition.

An Israeli air strike was reported to have killed a Hezbollah leader in Damascus on Saturday in the latest attack on the Iranian-backed group in Syria by Israeli forces.

And while the United Nations Security Council on Friday approved a resolution backing plans for a Syria peace process, obstacles to ending the war remain daunting, with no side able to secure a clear military victory.

HEAVY PRICE

The death of the Revolutionary Guard members is an indication of Iran’s increased involvement in fighting in Syria - and the heavy price its soldiers are paying - as it props up a Syrian army hit hard by nearly five years of conflict.

“The Iranians have increased the extent of their direct military involvement in the conflict mostly in order to make up for the heavy attrition among Syrian army units,” said Hilal Khashan, a political science professor at the American University of Beirut.

The Syrian army has recently had to take a back seat as Iran and its allied militias take the lead in the fight against the opposition.

“The SAA (Syrian Arab Army) is a gutted institution,” said a Western diplomat in Beirut who asked not to be identified. “There’s defections, there’s fleeing.”

The timing of Iran’s increased involvement in the conflict, particularly in the fight for control of Aleppo, was coordinated with the start of Russia’s air campaign in late September.

The Iranians have shown their commitment to the new effort and coordinated operations on the ground by sending in senior commanders like Hamedani, who played a key role in suppressing protests following the disputed 2009 presidential election in Iran.

The influx of Iranian troops, along with Russian air support, allowed the Syrian army to break the siege of the Kweiris airbase in Aleppo province in early November but otherwise the new coalition has made only incremental gains around Aleppo.

And while Hamedani may have been individually targeted by Islamic State, the bulk of the Guard commanders who have been killed recently died in combat.

“They were killed in clashes,” said Rami Abdulrahman, who runs the British-based Syrian Observatory for Human Rights, which monitors the war via contacts on the ground.

That is not a new development for Iran: Guard commanders regularly visited frontline troops during the Iran-Iraq war in the 1980s. It was a way to boost morale and show camaraderie with ordinary soldiers.

“At the time of the Iran-Iraq war it was the same: high- ranking officers from the Revolutionary Guards would go to the front lines and sometimes they would get killed,” said Mohsen Sazegara, a founding member of the Revolutionary Guards who is now a U.S.-based dissident.

“It’s a tactic. They see it as a kind of sacrifice so they don’t sit in the back and let others fight.”

FRONT LINES

Among those who have made a point of visiting the front lines in Syria is Qassem Soleimani, the head of the Quds Force which is tasked with carrying out the Guards’ missions outside Iran’s borders.

Last month, an Iranian opposition group said Soleimani was injured in fighting near Aleppo though the Iranian media later published quotes from him saying he was not hurt.

The Iranians dying in Syria now are not only members of the Quds Force. For months, the Revolutionary Guards have also been sending rank and file members, who do not have experience fighting outside Iran, to join the war in Syria. As a result, the organization has had to adapt.

“The Revolutionary Guard is changing the outcome of the war in Syria but the war in Syria is also changing the nature of the Revolutionary Guard,” said Ali Alfoneh, a senior fellow at the Foundation for Defense of Democracies and an expert on the Revolutionary Guards.

“The consequences of the war in Syria for the Revolutionary Guard are huge. The Quds Force used to be a very small part of the Revolutionary Guard now you’re seeing the transformation of the Revolutionary Guard into one big Quds Force.”

For now, the high number of deaths in a relatively short period does not appear to have reduced the commitment of the Guards to the conflict in Syria.

“Iran can maintain the current level of its involvement in Syria and even increase it,” said Khashan. “It would be counterproductive to quit at this advanced stage in the conflict.”

Despite the combat deaths in Syria, there has not been a huge public backlash against the war or the Guards among ordinary Iranians. That is largely because many of them have, to some extent, accepted the government message that Islamic State, which has threatened to carry out attacks in Iran, represents an existential threat.

“No one wants to shed Iranian blood to save the throne of Bashar al-Assad but everyone hates Islamic State,” said Alfoneh.

“The public is proud of their family members fighting and even losing their lives against an anti-Iranian, anti-Shi’ite force,” he said. “They generally believe they’re on the right side of history this time.”