By James Fallon and Ayham Kamel

On May 21, the Lebanese Armed Forces shot and killed prominent Sunni Sheikh Ahmed Abdul Wahed as his convoy passed through a checkpoint, triggering gun battles in Beirut's Tariq al Jdeideh neighborhood between two Sunni political parties, the anti-Syrian Future Movement and the pro-Syrian Arab Movement Party. The fighting followed clashes between Alawites and Sunnis in Tripoli in response to the arrest of Shadi al Mawlawi, a Sunni Salafist activist accused of aiding the Syrian opposition. Clearly, Syria's troubles have crossed the border into Lebanon.

In fact, Syria's turmoil is polarizing Lebanese factions and threatening the country's delicate political balance. Conflict in Syria has fallen largely along sectarian lines, and it is now fueling sectarian tension in Lebanon. The majority of protesters facing daily violence from the Syrian regime are Sunni, and this has driven moral and material support for their cause from Lebanon's mainly Sunni north. To avoid confrontation with his Sunni community, Prime Minister Najib Mikati has not actively interfered to stop such assistance, creating a perception that his government is at least tacitly complicit in supporting rebels.

Ironically, the one cross-sectarian institution in Lebanon that many consider capable and trustworthy -- the country's armed forces -- is a problematic tool for ending street violence between Lebanon's political parties. On the one hand, the sectarian diversity within the army gives it some level of credibility with all of Lebanon's various factions. In fact, in May 2008, when Hezbollah gunmen fought Sunni militias for control of mainly Sunni neighborhoods in west Beirut, the army helped defuse tensions on both sides -- greatly bolstering its credibility and national popularity. Yet, then as now, the army could not directly intervene to stop the bloodshed, because the sectarian fault lines that run through the country's politics and society are also apparent within its ranks. Prime Minister Najib Mikati knows that if he calls on them to engage directly, there's a risk that soldiers will join the various fights instead of breaking them up.

Recent unrest is exacerbating this fear. During clashes on May 21, Sunni gunmen directed their fire at the army. Following the checkpoint shooting, the army withdrew from some positions in the north, and several Sunni politicians called for a more permanent expulsion. The military's response was measured, but the rise of militant factions in northern Lebanon is making it much harder for the army to intervene in battles in which its soldiers may feel they have a stake. These conditions could be an indication that the army's tenuous role as super-sectarian arbiter is deteriorating among some Lebanese, particularly the Sunni population. As the Sunni-dominated northern region of Tripoli and its surroundings continue to serve as a logistical base for Syrian rebels, we'll probably see more of these clashes, and the government's ability to deploy forces without risking its credibility will definitely diminish.

Political instability is likely to rise in Lebanon as the Syria crisis worsens, and efforts better spent on the already difficult task of governing will be redirected toward buttressing the fragile balance necessary to maintain any government at all. Lebanon's political institutions have proven resilient in the face of serious challenges over the years, but that resilience is often the result of choosing to do nothing that might fan the country's flames.

Inaction may avoid making matters worse, but it does little to resolve the underlying causes of persistent instability in Lebanon.

James Fallon is an associate with Eurasia Group's Middle East practice. Ayham Kamel is an analyst in the firm's Middle East and North Africa practice.

By Hani Sabra and James Fallon

There is no shortage of theories on why Saad Hariri has abruptly retracted his accusation that Syria was "involved" in the 2005 assassination of his father. Some say that Syrian or Iranian threats forced the about-face. Others say the Lebanese premier must have finally realized last week that Syria is truly innocent -- and that someone else is the guilty party.  

Neither scenario sounds plausible. Hariri probably still believes that "Syria" was involved, but he has chosen between competing priorities that have become increasingly impossible to pursue simultaneously: the drive to find his father's killers and the need to govern Lebanon.

Several factors likely went into his decision. Hariri's anti-Syria position no longer enjoys solid international backing, and domestic problems are becoming harder to solve without removing this elephant from the room. Saudi Arabia wants to "break the Iran axis," and is courting Syria to further isolate Tehran. Important players in Lebanon's stability, the Saudis need Hariri to give Damascus some breathing room.

In addition, Saad Hariri can't govern Lebanon by himself. His anti-Syria March 14 coalition is shrinking, and his influence with other key players has waned, particularly since Druze leader Walid Jumblatt made an early exit following parliamentary elections in June 2009. Most important is the calculation involving Hizbullah, Syria's most important ally in Lebanon. Beyond easing pressure on Syria, Hariri is also undermining the ongoing work of the U.N.-backed Special Tribunal for Lebanon, which may well indict members of Hizbullah in the murder in the not-too-distant future. The retraction should ease some of the frictions between his government and the country's most powerful political force.

Consensus is always necessary to govern in Lebanon, but now it is becoming increasingly impossible for Saad to even remain premier without dropping the issue of his father. Hariri may also see this as a chance to reduce the likelihood of Sunni-Shia conflict inside his country, and to move Lebanon out of its protracted political stalemate.

But there's one other issue. Look closely at what Hariri actually said. Many of his supporters are left bewildered by his reversal, but these were his words:

"I have opened a new page in relations with Syria since the formation of the government ... One must be realistic in this relationship and build it on solid foundations. One should also assess the past years, so as not to repeat previous mistakes. Hence, we conducted an assessment of errors committed on our behalf with Syria, and I felt for the Syrian people, and the relationship between the two countries, we must always look to the interests of both peoples, both countries and their relationship. At a certain stage, we made mistakes. We accused Syria of assassinating the martyred premier, and this was a political accusation."

He never said "Syria didn't do it," and he made no mention of Hizbullah. He's stepping away from an accusation that has made life more difficult. He's allowing himself to appear above the political fray without sacrificing his credibility completely with his anti-Syrian, anti-Hizbullah political base before the tribunal finally issues indictments against Hizbullah operatives -- which it may do soon.

Hani Sabra and James Fallon are analysts in Eurasia Group's Middle East practice.