Hezbollah fighters carry the coffin of fellow militant Mohammed Ahmed Zbibo, who was killed during fighting against jihadists and other Syrian opposition fighters in the Qalamun mountains along the border with Syria. (AFP/Getty Images)

Hezbollah has won grudging respect, even from some foes, for its tenacious guerrilla campaigns against Israel. But now Lebanon’s most powerful military organization is losing its aura of invincibility.

Tactics that the Shiite group has used against Israeli soldiers are being inflicted on its own forces­ by militants from the Islamic State and the al-Qaeda-affiliated Jabhat al-Nusra, which have carved out footholds in Lebanon along the porous Syria border.

The growing number of attacks and kidnappings by the Sunni militants represent the opening of yet another military front for Hezbollah. It already has thousands of troops deployed in Syria to bolster President Bashar al-Assad’s regime, while still more are facing Israel in southern Lebanon.

“Hezbollah is spread thin. They are waging so many battles and are positioned on so many fronts,” said Imad Salamey, associate professor of political science at the Beirut-based Lebanese American University.

Classified as a terrorist organization by the United States and European Union, Hezbollah was created in the turmoil following Israel’s 1982 invasion of Lebanon. The militant group forced Israel to end its occupation of southern Lebanon in 2000 and inflicted a heavy blow on Israel during a 34-day war in 2006. Hezbollah’s forces­ are better armed than Lebanon’s army, which plays a subordinate role.

Members of the Lebanese Resistance Brigades, a Hezbollah armed and funded militant group, attend a rally commemorating “Liberation Day,” which marks the withdrawal of the Israeli army from southern Lebanon in 2000, in the southern border town of Bint Jbeil, Lebanon. (Hussein Malla/AP)

Hezbollah also developed expansive charitable networks and a political movement that exerts considerable influence over the country’s parliament.

The group owes its power, in part, to an ample supply of weapons from the Iranian and Syrian governments, which form an anti-Western axis that allows Tehran to project influence to the Mediterranean and Israel’s borders. The weapons are largely funneled through Syria.

So when Assad’s forces­ started sustaining serious defeats in the civil war, Hezbollah was compelled to intervene to keep open those supply lines.

As many as 5,000 of its foot soldiers are thought to be in Syria, where they have played a crucial role in reversing gains by the Sunni-led opposition. But the costs of Hezbollah’s involvement have been mounting.

Although exact figures are not available, hundreds of its fighters have been reported killed in Syria. The demand for replenishing troops has forced the group to lower its recruitment age — funerals for fighters as young as 16 are being held in Shiite communities that dot the Bekaa Valley area of northeastern Lebanon.

Hezbollah wants to extricate its forces­ from Syria, said Lina Khatib, director of the Beirut-based Carnegie Middle East Center, but it knows they have to remain there until “there is a political deal acceptable to Iran.”

Meanwhile, Hezbollah is facing strain from increasing assaults by fighters from the Islamic State and Jabhat al-Nusra, who have spilled across the border from Syria.

A Hezbollah militant looks through his binoculars in Umm Khorj in the Lebanese eastern mountain range close to the Syrian border. (Sam Skaine/AFP/Getty Images)

Maintaining its image

The Sunni militants began setting off devastating car bombs and launching suicide attacks a year ago against Hezbollah strongholds across the country, including the Shiite suburbs of southern Beirut.

In August, militants from the two extremist groups stormed the northern Lebanese city of Arsal and captured more than 20 policemen and soldiers before withdrawing. Analysts suspect the jihadists may also be holding a number of Hezbollah fighters. The militants beheaded at least two of the soldiers and demanded that Hezbollah withdraw from Syria.

Then, on Oct. 5, Jabhat al-Nusra carried out a series of assaults against Hezbollah positions in the Bekaa Valley. The Sunni militants killed eight Hezbollah fighters and published video footage of the grisly aftermath. Embarrassed, Hezbollah reportedly pressured Web sites to have the video removed.

“This attack was really striking. It really damages­ the reputation of Hezbollah as a competent military force,” said David Schenker, director of Arab politics at the Washington Institute for Near East Policy and a former Pentagon official.

Hezbollah’s response was swift if unexpected. Two days after the attack, it set off a bomb in what had been a relatively quiet southern border town, injuring two Israeli soldiers. It warned afterward that it was still able to confront Israel despite its military commitments in Syria.

Schenker said Hezbollah targeted Israel “to show everyone that they are still capable of sticking to their bread-and-butter issue.”

Some analysts say the incident is a sign that Hezbollah is becoming reckless because of concern over being perceived as weak. The consequences of such behavior could be grim: Hezbollah’s capture of two Israeli soldiers in 2006 triggered a devastating war.

“If Israel wanted to launch a war against Hezbollah, this would have been a perfect opportunity, and this time around, Hezbollah’s losses­ would be huge,” Hanin Ghaddar, managing editor of the Lebanese Web site Now News, wrote in an editorial.

A week after that attack, Hezbollah’s leader, Hasan Nasrallah, made a rare public appearance, showing up in the Bekaa Valley to greet families of fallen fighters. Lebanese news media reported that he also visited Hezbollah soldiers there.

The visit was partly intended to assuage frustration among Shiite families who have lost loved ones in Hezbollah’s military engagements, analysts said.

A few cracks are showing in the taboo against speaking negatively about Hezbollah’s military endeavors. Such talk, however, remains limited.

“I have had a lot of problems when I’ve talked about my anger over what happened to my brother,” said a Shiite woman whose sibling was killed seven months ago while fighting with the group in Syria. She spoke on the condition of anonymity for fear of retaliation.

An analyst close to Hezbollah said the Nasrallah visit also was aimed at keeping the area’s Shiite clans from retaliating against neighboring Sunni communities after a spate of attacks and kidnappings. The communities have been feuding, in part, because of their support for opposing sides in the Syria conflict. Lebanon’s feuding religious groups fought a 15-year civil war that ended in 1990.

“Hezbollah is trying to keep the situation as calm as possible,” said the analyst, who also spoke on the condition of anonymity, citing fear of angering Bekaa Valley clans.

Hezbollah has sought to prevent a deterioration in the area’s security by increasing training and arms for a number of villages­ with Shiite and Christian residents.

Some residents also have begun organizing their own de­fenses, fearing clashes with Sunni militants who are increasingly entering the area. A 39-year-old Christian resident of Ras Baalbek, Jad Rizk, joined impromptu neighborhood patrols after the jihadists took Arsal during the summer.

The residents hope for protection from Hezbollah, but with the group exposed on many fronts, they are not taking any chances­.

“As civilians living in a Christian village, we had to pick up arms to protect ourselves,” said Rizk, a lawyer and father of two young children.

“Every family has done the same.”

Suzan Haidamous contributed to this report.