The Lebanese army recently defeated a challenge from a militant Salafist group led by radical Sunni cleric Sheikh Ahmad al-Assir near the southern city of Sidon. The clash was a symptom of an increasingly treacherous witches’ brew bubbling away in Lebanon: Shia and Sunni communities are dangerously polarized. Salafist groups are rising in strength as Hezbollah gains power. The Lebanese political system is paralyzed. And spillover from the war in Syria is adding fuel to the fire.

Amid this tumult, the importance of the army has once again been underlined. The episode highlights the central part the army plays as an institution that enjoys fairly widespread national legitimacy. It puts out security fires and tries preserves precarious stability and security in the country—a role that will become all the more important as the crisis in Syria escalates further. Outside actors would do well to maintain and bolster their support for the army.

The fighting started on the morning of Sunday, June 23, when al-Assir’s followers opened fire on an army checkpoint. The clashes escalated rapidly. Attempts by other Islamic clerics to find a negotiated solution failed, and the army command vowed to resolve the challenge by force.

By Monday evening, the army had prevailed and taken over the group’s compound. Eighteen members of the military died in the fight, and over 100 were wounded. Al-Assir’s followers suffered heavier losses, and some of them surrendered to the army, but the leader himself evaded capture and escaped to a still-unknown location.

Al-Assir rose to prominence over the last two years by openly challenging Hezbollah and calling for jihad in support of the Syrian rebels’ fight against the regime of Syrian President Bashar al-Assad. He gained popularity for saying publicly what many in the Sunni community thought privately and what other mainstream Sunni politicians avoided voicing. However, this popularity—amplified by local media—did not translate into a large organized following.

He had been apparently consolidating an armed compound in the town of Abra, east of Sidon, with a following of Lebanese, Syrian, Palestinian, and other fighters who espoused a radical Salafist and jihadist creed. The army had been closely monitoring the group’s evolution and had set up checkpoints near its compound, one of which was attacked and sparked the battle.

A number of Salafist groups and sympathizers took to the streets of some neighborhoods in Tripoli and Beirut in support of al-Assir and denounced the army. They particularly berated the army for acting only against Sunni armed groups while turning a blind eye to the country’s main armed Shia group, Hezbollah, and its massive militia and state-within-a-state. Al-Assir and his followers claimed that they were arming themselves in part because Hezbollah was increasing its armed presence within the majority-Sunni city of Sidon. That the army looked the other way when Hezbollah took over Beirut in May 2008 and sent units across the border to fight alongside the Assad regime also fed the ire of al-Assir’s supporters. Unconfirmed reports that Hezbollah fighters had joined the army in fighting against the Sunni group made matters worse.

While many in the Sunni community sympathized with many of al-Assir’s positions against Hezbollah, the influence of the Shia regime in Iran, and the Assad government, the Salafist attack on the army pushed al-Assir outside the pale of mainstream opinion. The majority within the Sunni community, as well as most others in Lebanon, strongly identify with the army and realize that the army is what stands between stability and a descent into full state failure and ruinous civil war.

The main Sunni party in Lebanon, the Future Movement, which opposes Hezbollah, shares some of al-Assir’s critiques of the army, but its leaders and other mainstream Sunni politicians came out in support of the army in this clash. Many of them blamed Hezbollah for setting the much larger precedent of being a nonstate armed organization in defiance of the national government and warned that reproducing that model within their own community would be a sure road to ruin. The objective, they argued, was to get Hezbollah to eventually give up its arms and accept government authority, not to have new groups arm themselves and further erode the authority of the state.

The latest episode may have been a defeat for al-Assir and his group, but it is a symptom of growing levels of serious discontent within the Sunni community, the inability of mainstream Sunni movements to contain it, and the gradual rise of radical Salafist groups. Although they remain a minority within the community, militant Salafist groups now have significant footholds in all the main Sunni areas of Lebanon, including the cities of Tripoli, Beirut, and Sidon. They receive funding from sympathetic networks in the Gulf and are joined by radical Syrians and others engaged in the broader fight against the Assad regime and Hezbollah. Flags of Jabhat al-Nusra, the prominent Syrian jihadist group linked to al-Qaeda, were found in al-Assir’s compound, and many of his fighters were Syrian, possibly from the growing refugee community in the country.

The battle was reminiscent of a much larger confrontation in 2007 between the army and the Fatah al-Islam jihadist group in the Nahr al-Bared Palestinian refugee camp near the northern town of Tripoli. That battle went on for months, but there too the army prevailed, although after heavier losses.

This time around, the dangerous confluence of forces in Lebanon could easily have led to a major collapse of order and the eruption of sectarian fighting in Sidon, Beirut, and Tripoli. Sectarian polarization in Syria, Hezbollah’s open fighting alongside the Assad regime, and growing Sunni radicalism in Lebanon might mean that the army’s victory has only postponed a dangerous confrontation that is yet to come.

What Lebanon needs most to avoid such a future is the rapid de-escalation of the crisis in Syria. The proposed peace conference, dubbed Geneva II, has little hope of achieving a resolution to the Syrian conflict. But it could potentially help de-escalate the crisis in the short term. It could lean on both sides to work toward establishing ceasefires and scaling back fighting. Outside parties should agree to dramatically increase humanitarian and refugee aid. And the process should help convince Russia and Iran to encourage Hezbollah to scale back its dangerous engagement in Syria and press Gulf countries to take action against networks that might be providing support to dangerous jihadist groups inside Lebanon.

More directly, the crisis should be a clear demonstration to the regional and international communities that they must continue providing financial and material support to the Lebanese army and—if anything—increase it.

But it is equally apparent that Lebanon can no longer afford to dither about forming a government of national unity that brings in the main political parties from all communities to bear responsibility for the country’s stability in this difficult time. Hezbollah wagered that it could bring down the previous Lebanese government of Najib Mikati and help the Assad regime defeat its opponents in short order. The Future Movement bet that Hezbollah’s involvement in Syria would isolate it regionally and internationally and that it could push for a government that excluded the Shia group. Neither approach is working.

Lebanon needs to be governed by cooperation and broad consensus—especially in times of acute sectarian tension. It is far better to have the opposing parties inside the government and publicly responsible for the country’s stability than to have them on the outside pursuing their own agendas without any such accountability.

The regional and international communities, as well as Lebanon’s own leaders, should realize that the latest battle east of Sidon might be one of the last warning signs before Lebanon’s eruption into widespread sectarian fighting. Indeed, the first real sparks of the long 1975–1990 Lebanese civil war took place in Sidon. Rapid action is needed.