In the shadow of the Israeli-Palestinian conflict in Gaza, fighters from the jihadist Islamic State (ISIS or IS) crossed the Syrian-Lebanese border to the town of Arsal in northern Lebanon in an effort to seize control of a Syrian rebel base camp. The incursion, which began on August 2, has led to direct clashes between Islamist insurgents and the Lebanese army, marking a dangerous spillover of regional conflicts onto Lebanese soil. Indeed, despite its attempts to remain untouched by the turmoil in its neighborhood, Lebanon is already deeply entangled in the upheaval.

Officially, Lebanon has a policy of dissociation from surrounding conflicts, including the turmoil in Syria. Declared by the Lebanese ministerial cabinet, the policy is applied by Lebanon’s security forces, which among other things monitor the traffic of refugees crossing the border from Syria and focus on preventing armed groups from fighting in Lebanese towns. Syrian rebels have settled in Lebanese border towns since the outbreak of the Syrian revolution, but the Lebanese army has rarely engaged in armed confrontations with them. In southern and northern Lebanon, though, the army and security forces have fought several battles against Sunni Islamist extremist groups seeking to destabilize Lebanon and to control Sunni towns and cities.

Mario Abou Zeid
Abou Zeid was a research analyst at the Carnegie Middle East Center, where his work focuses on political developments in Lebanon, Syria, Iraq, and Iran.
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One Lebanese actor in particular has remained directly involved in the conflict in Syria. The Lebanese paramilitary group Hezbollah has been actively supporting the regime of Syrian President Bashar al-Assad, safeguarding its weapons stockpiles in Syria and supply lines across the Syrian-Lebanese border. Hezbollah has also fought rebels in Syria alongside the Syrian army.

Initially, the Assad regime, and by extension Hezbollah, did not fight ISIS as the extremist group started to take over Syrian territory. It disregarded—even encouraged—the Islamic State’s expansion because the group was operating in areas controlled by the opposition. ISIS scattered the Syrian opposition; pushed back its most effective armed group, the Nusra Front; ousted a moderate Islamic armed group, Ahfad al-Rasoul, from the town of Raqqa; and crushed the Northern Storm brigade (in the town of Azaz). Syrian opposition groups, more poorly equipped and trained than the Islamic State, couldn’t match ISIS fighters. The rise of the Islamic State was also a golden opportunity for the Assad regime to justify its struggle against the Syrian opposition, as the regime presented ISIS to the international community as a proof that the regime is struggling with terrorists.

As ISIS pursued its expansionist agenda of creating a Sunni heartland between Iraq and Syria, Hezbollah became one of the group’s enemies. ISIS advanced into Iraq in June 2014 and appropriated resources, funds, and advanced weapons. The increasingly capable ISIS soon became an inconvenience for the Syrian regime, which was pushed into direct confrontation with the group for the first time. Consequently, Hezbollah also found itself facing a powerful enemy.

With Hezbollah clearly an enemy, ISIS moved its fighters into Qalamoun, an area on the Syrian-Lebanese border overlooking Syrian territories that is of strategic importance to Hezbollah. Arsal, at the foot of the Qalamoun mountain range, is key for both ISIS and Hezbollah. For ISIS, Arsal, a Sunni-majority town harboring sympathizers with the Syrian revolution and 100,000 Syrian refugees, is considered a base for fighters to regroup and go back to the conflict in Syria. For Hezbollah, Arsal is the last safe haven for Syrian rebels in Qalamoun; Hezbollah has secured all other access points to the mountain range where the rebels can take refuge. The Lebanese Armed Forces, unwilling to become entangled in a fight with the Syrian rebels and under continuous pressure from Hezbollah, had installed checkpoints around Arsal, preventing any armed groups from going outside the town and disregarding their flow back and forth across the border.

Hezbollah calculated that pushing ISIS fighters into Arsal would trap them in an open a clash with other Syrian rebel groups in the town—notably the Nusra Front and the remainder of an amalgam of fighters who had fled or lost battles in Syria (such as battles for the towns of Quseir, Yabroud, Raqqa, and Azaz). ISIS could potentially be hurt without the need for Hezbollah to engage with the group. Such a confrontation would naturally drag the Lebanese army into the fight because, taking place in Lebanon, the fight would present a direct threat to Lebanese stability.

A Lebanese army takeover of Arsal would benefit Hezbollah, and the Assad regime as well, in its bid to control the Qalamoun area. From a military perspective, it would cut an essential supply line for any Syrian rebel group operating on the border. It would guarantee the safety of Hezbollah’s fighters by preventing Syrian rebels from accessing the border. And there is also the issue of a grant Saudi Arabia gave the Lebanese army in spring 2014 to purchase advanced weaponry—weapons that would help the army counter Hezbollah’s advanced arsenal. Engaged in the fight against the insurgents, the Lebanese army would use up that support without posing a potential serious threat to Hezbollah’s military supremacy in Lebanon.

When Lebanese officials arrested Imad Jomaa, the leader of ISIS in Qalamoun, in early August, the Lebanese army was finally dragged into a confrontation with ISIS. This has put pressure on the Lebanese army, and has undermined Lebanon’s dissociation policy.

This development was inevitable. For the Lebanese army to succeed in implementing the policy of dissociation, it would have to be the sole Lebanese armed group taking action on the ground and observing and controlling Lebanese borders in order to prevent any potential spillover of the Syrian conflict. But the army possesses neither the equipment nor the personnel to execute this role. This is in large part because the current political status quo in Lebanon, in which Hezbollah holds the upper hand over state institutions, has kept the Lebanese Armed Forces in a subordinate position.

And as long as Hezbollah operates outside the umbrella and command of the Lebanese Armed Forces—and by extension outside the policies of the state institutions—Lebanon will remain entangled in upheaval spilling over from regional conflicts.

Correction: An earlier version of this article incorrectly identified the arrested ISIS leader as Ahmad Jomaa. This has been corrected to Imad Jomaa, also known as Abu Ahmad.