By , Correspondent 

As the first rains of the approaching winter lash the rugged mountains along Lebanon’s eastern border with Syria, Lebanese officials fret that militants belonging to the self-described Islamic State and allied factions could be preparing to break out of their isolated mountain strongholds, threatening populated areas.

In response, the United States is speeding the delivery of ammunition to the Lebanese Army, while Hezbollah, which also is fighting the Sunni IS and other groups, is making small arms available to its local Shiite supporters.

In recent days, the Lebanese Army, which is heavily deployed around the key town of Arsal in the northeast Bekaa Valley, has thwarted several apparent probes by militants seeking to reach the town for resupply. And 20 miles south of Arsal, militants from Al Qaeda-linked Jabhat al-Nusra, last week briefly attacked and overran a mountain-top outpost manned by fighters from the Iran-backed Hezbollah, killing several Shiite fighters.

Further south still, near the border village of Shebaa at the junction of the Lebanon-Israel and Syrian frontiers, Lebanese troops have reinforced their positions against potential infiltrations by Jabhat al-Nusra, which has seized territory in adjacent Syria.

“The problem is no longer just around Arsal. The threat now exists along the entire border from Shebaa to Tartous,” says Basem Shabb, a Lebanese parliamentarian with the Western-backed March 14 coalition. Tartous is a Syrian city on the Mediterranean coast 17 miles north of Lebanon’s border.

In the conflict involving the Islamic State that spans the Middle East from the Mediterranean to the Iraq-Iran border, Lebanon represents the western flank. Despite coming under daily air strikes in Iraq and Syria by the United States-led anti-IS coalition, the jihadist group, numbering an estimated 31,000 fighters, appears poised to capture the Kurdish Syrian town of Kobane on the border with Turkey and has reached the western and northeastern approaches of Baghdad, the Iraqi capital.

The threat to Lebanon, however, does not appear to be part of a broader strategy by IS to add territory to its self-proclaimed “caliphate” so much as the unintended consequence of battlefield successes against the group. In an offensive mounted by Hezbollah and Syrian troops earlier this year, IS and other Syrian rebel factions were pushed into Lebanon’s remote eastern border from the mountainous Qalamoun region north of Damascus.

In other parts of Syria, the IS and Jabhat al-Nusra are mortal enemies. But along the Lebanon-Syria border, they have forged a tactical alliance out of necessity against Hezbollah and the Lebanese Army. 

On Aug. 2, a combined force of several hundred fighters from IS, Jabhat al-Nusra, and the Free Syrian Army attacked Lebanese Army posts in Arsal, a large Sunni-populated town that has served as a hub of support for the Syrian opposition. After several days of clashes, the militants retreated back to the mountains to the east of the town, taking with them large amounts of looted weapons and ammunition and some 36 Lebanese soldiers and policemen. Three of the hostages have been executed and several released. The remaining hostages number around 20 and are split between IS and Jabhat al-Nusra custody.

Since then, the Lebanese Army has deployed reinforcements to Arsal, set up artillery batteries covering the eastern mountain range, and begun building heavily fortified positions to protect the town from further assaults.

Concerns of another attack have grown as the hot summer ends and the colder weather begins. The mountains along the border rise up to 8,500 feet and are capped in snow during the winter, making for a bleak environment for the militants who live there in caves and abandoned farmhouses.

Some analysts suspect that the IS and its allies may try to break out of the mountains by punching through army lines around Arsal and seeking shelter with Sunni supporters in Tripoli, Lebanon’s second largest city.

Local residents arming themselves

The fear of a breakout by IS has spurred residents of Christian and Shiite villages in the northern Bekaa to arm themselves and mount patrols.

“Imagine if they make it into Ras Baalbek and crucify a Christian in the central square. It will set Lebanon alight,” says a European diplomat in Beirut, referring to a Christian village five miles north of Arsal.

In recognition of the gravity of the situation along the eastern border, the US has expedited the transfer of large quantities of ammunition, including advanced Hellfire missiles, to bolster the Lebanese Army’s defenses.

Hezbollah also has been helping its core Shiite constituency to protect themselves lately by flooding the black market with several thousand AK-47 assault rifles, according to several sources close to the party and Lebanese arms dealers. The rifles had the identifying moniker of the “Abbas Brigades” – a Hezbollah fighting unit – removed from the stocks along with serial markings on the metal work and were sold in green plastic bags for around $1,300 to $1,400 each, some $400 or $500 less than the market price for an AK-47.

“The rifles were snapped up in no time. People are nervous and are looking to protect themselves,” says a Shiite close to Hezbollah who saw the rifles.

In the past three weeks, Lebanese troops have come under isolated grenade and shooting attacks in Tripoli and the impoverished mainly Sunni province of Akkar to the north, where there is some sympathy for IS and other Islamist factions in Syria. Many Lebanese Sunni radicals accuse the army of cooperating with the powerful Hezbollah against their community. Since July, four Lebanese soldiers, all Sunnis from north Lebanon, have deserted from the army and joined IS or Jabhat al-Nusra.

Sunnis urged to attack Hezbollah

On Monday, Zirajeddine Zureiqat, the leader of the Lebanon-based and Al Qaeda-inspired Abdullah al-Azzam Brigades, urged supporters to refrain from attacking the Lebanese Army, which he said was merely a “tool” in Hezbollah’s hands. He instructed Sunnis to attack Hezbollah, the “puppet master,” instead.

“You have the party’s [Hezbollah’s] centers, checkpoints, supply lines, leaders, and members across Lebanon. Kill them and avenge the children of Lebanon and Syria,” he said in a statement on his Twitter feed.

Hezbollah has enraged Sunnis in Lebanon and across the region with its deep involvement in the war in Syria in which it is defending the regime of Syrian President Bashar al-Assad. Hezbollah has built a string of outposts on mountaintops behind Shiite villages in the northern Bekaa.

A surprise attack Oct. 5 near the Bekaa village of Brital against several Hezbollah outposts, one of which was briefly over-run, points to further battles on Lebanese soil in the weeks ahead pitting IS, Jabhat al-Nusra, and other Syrian factions against their Shiite foes.

In a pep talk Monday to Hezbollah fighters in the Bekaa Valley, Sheikh Hassan Nasrallah, Hezbollah’s secretary-general, vowed that the party would remain on the path of “confrontation.”

“There is no room for surrender or defeat, whatever the size of confrontation or pressures,” he was reported to have said. “Let them know that resistance, which is always vigilant, will protect any attempt to attack Lebanon or its people… and in the end great victory will blossom.”