LABWE, LEBANON — Lebanon’s militant Shiite Hezbollah organization has begun sending fighters as young as 16 to the battlefields of Syria, an indication that the Shiite army is being stretched between fighting Sunni jihadis in Syria and a desire to keep a cutting edge in reserve for a possible future showdown with Israel.

Until now, Hezbollah had required fighters to be at least 18 years of age. The lowering of the age restriction could indicate that the Iran-backed party is feeling hard pressed as its cadres fight from Aleppo in north Syria to Deraa Province in the south, as well as dispatching advisers and trainers to the new battlegrounds of Iraq.

The party leadership is holding back experienced fighters specifically trained to fight Israel, such as anti-tank missile units and long-range rocket teams. But the organization now finds itself engaged in a war against ruthless Sunni militants from the rugged mountains of east Lebanon and across Syria to the borders of Iraq and Iran that is slowly transforming the way Hezbollah sees its military role.

Sheikh Hassan Nasrallah, Hezbollah’s leader, has emphasized the threat posed to the region by groups such as the Islamic State of Iraq and the Levant (ISIS), also known as the Islamic State, which has seized vast tracts of territory across northern Syria and Iraq and committed massacres against minorities.

“We have to believe that there is a real existential danger threatening us all and it is not a joke,” Sheikh Nasrallah said during a speech on Friday commemorating the end of a month-long war with Israel in 2006. “The so-called [IS] is a group that has now seized large geographical areas in Syria and Iraq and taken control of [oil and gas] fields and main water dams.… The massacres that have been committed harmed Sunnis primarily and [IS] did not spare anyone in Iraq like Kurds, Yazidis, Shiites, Christians, Turkmen… this example has nothing to do with Islam.”

Sucked back in

When IS and allied Iraqi Sunni groups overran Mosul in early June, some Iraqi Shiite paramilitary forces fighting alongside the Syrian Army and Hezbollah in defense of Syrian President Bashar al-Assad were recalled to Iraq to face the new threat. Syrian rebel groups took advantage of this in the strategic Qalamoun area north of Damascus and adjacent to Lebanon’s eastern border to mount counterattacks against pro-Assad forces.

Hezbollah had spearheaded a campaign between last November and early April to drive rebels from Qalamoun. But the renewed fighting sucked Hezbollah back into the area, and fighting has spilled across the border into Lebanon, where Hezbollah is battling a few thousand determined Syrian and Lebanese Sunni fighters drawn from an array of factions, including IS and Jabhat al-Nusra, Al Qaeda’s Syrian affiliate.

Hezbollah’s adversaries have put up a stiff fight in the mountains east of the Shiite villages of Nahle and Younine, the Sunni town of Arsal, a bedrock of support for the Syrian rebels, and the Christian village of Ras Baalbek.

The Lebanese Army was drawn into the fighting on Aug. 2 when militants attacked Arsal after a top Jabhat al-Nusra leader was arrested. According to people close to Hezbollah and Shiite residents of the northern Bekaa Valley, Hezbollah assisted the Lebanese Army by firing mortar rounds and artillery rockets at the Sunni militants in the mountains outside Arsal.

“They [Hezbollah] were using their [reconnaissance] drones to find (IS) in the mountains, then they hit them with rocket fire,” says Abu Ali, a Shiite businessman from Hermel. He adds that Hezbollah’s Grad artillery rockets were fired toward the Arsal area from Hawsh Sayyed Ali, a small village near Hermel on the border with Syria, 21 miles north of Arsal.

Tough fight

Still, Hezbollah has suffered casualties at the hands of the Sunni militants, who have gained considerable combat experience in the past three years fighting against the Assad regime.

Last month, two Hezbollah fighters were buried in a joint funeral in the mainly Shiite neighborhood of Haret Hreik in the southern suburbs of Beirut. They were killed in a desperate battle with Sunni militants in the mountains near Nahle village in east Lebanon. Mohammed Awada, one of the two slain combatants, was only 16 years old.

In the past, Hezbollah allowed boys younger than 18 to join the party, participate in youth programs, and undergo some basic military training, but would not send them into combat until they reached 18. Awada’s “martyrs” picture on the front of his coffin and adorning the streets of the neighborhood showed a slim youth with a mop of dark hair who looked even younger than his 16 years.

Hezbollah generally does not disclose details of its fighting in Syria, but some of the mourners at the funeral provided an account of the battle, offering a rare insight into the intense fighting experienced by the cadres.

The 40-strong Haret Hreik unit was deployed onto a hill east of Nahle after another Hezbollah squad had seized it from Syrian militants. However, the Syrian militants used the rugged terrain to approach the Hezbollah men and launch a counterattack at close range. The Haret Hreik unit belatedly realized that they were ill-prepared. They had deployed with insufficient ammunition and the batteries on their walkie-talkies died so they could not call for back-up. And they didn’t have a single pair of binoculars to look for snipers.

The fighting raged for five hours against a Sunni force estimated at 250 fighters. One of the Hezbollah men, a grizzled veteran of Lebanon’s 1975-1990 civil war, said it was the most intense combat he had ever experienced.

“They were only 10 meters from us, yelling ‘we are coming to kill you, O Rafideen’,” said the Hezbollah veteran, using a slur for Shiites popular with Sunni jihadis. He requested anonymity as he was not authorized to speak to the media.

The battle ended when a Hezbollah rapid-reaction unit arrived on the hill having heard the shooting and been unable to radio the unit. The Sunni militants were eventually driven from the hill, but the Haret Hreik unit suffered 10 killed and 20 wounded, including the veteran combatant, who was shot in the leg while carrying the body of a dead comrade.

This post originally appeared in The Christian Science Monitor