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Why Lebanon Has Become Syria’s Most Dangerous Neighbor

How refugee returns, Hizbullah’s decline, and Assad-era remnants are pulling Beirut and Damascus toward confrontation.
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The Lebanese town of Aarsal on the border with Syria
The Lebanese town of Aarsal on the border with Syria. (SamerofNyx/Wikimedia/CC BY 4.0)

Table of Contents

Summary

Lebanon and Syria are navigating a fundamentally altered relationship following the collapse of Syria’s former regime and the emergence of a new transitional authority. Longstanding patterns of domination have given way to fragile, transactional engagement marked by mutual suspicion.

Core disputes include refugee repatriation, the fate of Syrian detainees in Lebanon, border security, arms smuggling, and the presence of former regime figures and armed dissidents operating from Lebanese territory. These issues are increasingly intertwined with domestic Lebanese politics, particularly ahead of upcoming elections.

While both states now interact as nominal equals, unresolved security and legal conflicts risk escalating into covert or overt violence, making the new relationship unstable and highly contingent on political outcomes in Beirut.

The relationship between Lebanon and Syria is undergoing its most significant transformation in decades. The fall of the Assad regime in December 2024 and the rise of a transitional government under Ahmed al-Sharaa have turned the traditional power dynamic on its head. Whereas the “old” tension was defined by Syrian hegemony over Lebanon, the “new” tension is characterized by fragile mutual suspicion between two states struggling to reinvent themselves.

At the core of this tension lie several unresolved and highly sensitive issues that cast doubt on the ability of both countries to compromise.

The Refugee Crisis

For years, the presence of nearly 1.9 million Syrian refugees constituted a major source of friction. In 2025, the narrative shifted from hostility to repatriation. Nearly 400,000 Syrians—some estimates claim as many as 600,000—returned from Lebanon in 2025 alone. Their departure created an almost critical labor shortage in sectors traditionally filled by Syrian workers.

While Lebanon seeks a swift and total return to ease its economic crisis, the new Syrian government has treated repatriation as a diplomatic bargaining tool. Damascus has at times imposed visa restrictions or retaliatory border measures when it perceives the Lebanese government as mistreating Syrians or moving too slowly on other bilateral demands.

The Syrian Prisoner Issue

Perhaps the most volatile unresolved issue is that of Syrian prisoners held in Lebanon. Damascus views many Syrians detained in Lebanon’s Roumieh Prison as “political prisoners” or “revolutionaries” who fought against a common enemy—Assad and Hizbullah. Beirut, by contrast, classifies many of the same individuals as terrorists responsible for attacks on the Lebanese Armed Forces (LAF).

Damascus has made the release of these prisoners a condition for full normalization. Lebanon’s refusal to free individuals with “blood on their hands” remains a major obstacle. Approximately 2,600 Syrian citizens are currently in Lebanese custody. Nearly 70 percent are held in pretrial detention, many for over five to ten years without formal charges, due to Article 108 of the Lebanese penal code, which allows indefinite detention for terrorism-related offenses. An estimated 200–500 prisoners in Roumieh’s “terrorism block” are former members of Jabhat al-Nusra or ISIS. The new Syrian government—often associated with former HTS elements—views them as political heroes; the Lebanese Army views them as perpetrators of the 2014 Arsal battles.

Negotiations have shifted from broad rhetoric to concrete legal drafts. Deputy Prime Minister Tarek Mitri has emerged as the central Lebanese negotiator, attempting to balance humanitarian imperatives with national security concerns. A second draft of a Judicial Cooperation Agreement has been under debate since late 2025. Lebanon has agreed in principle to transfer prisoners not convicted of murder. Syria, however, objects to a clause that would prevent it from granting blanket amnesties once prisoners cross the border. In late 2025, Lebanon released around 100 Syrians on bail and transferred 22 others as a goodwill gesture to keep negotiations alive.

There is widespread speculation that a major prisoner release or transfer could occur shortly before the May elections. For the current Lebanese government, the “repatriation of terrorists” to Syrian custody would represent a major electoral victory. Damascus, meanwhile, may time releases to favor Lebanese candidates or blocs willing to grant Syria advantageous trade or border concessions.

Arms Smuggling and the “New” Border

During the Assad dynasty (1970–2024), arms flowed into Lebanon to supply Hizbullah and other pro-Syrian factions. Since December 2024, both the direction and intent of these flows have changed. The Sharaa government has actively sought to dismantle Hizbullah’s supply lines through Syria, launching security operations in former strongholds such as Qusayr.

This has created a paradox. While many Lebanese welcome Hizbullah’s weakening, the Lebanese state struggles to control its side of the border. Syria accuses Beirut of being either too weak or unwilling to stop residual smuggling of drugs and light weapons, interpreting this as disrespect for the new Syrian administration.

Damascus has mined illegal crossings and conducted army sweeps in the Homs–Qusayr region, forcing Hizbullah to rely almost exclusively on Beirut International Airport. Under U.S. pressure, the Lebanese government has begun monitoring the airport more strictly. For the first time, direct military skirmishes between Hizbullah and the new Syrian Army have occurred. Clashes in early 2025 in the Qusayr district caused casualties on both sides, signaling the effective collapse of the so-called “Axis of Resistance.”

Hizbullah, Subversion, and Syrian Dissidents in Lebanon

Facing a hostile Syrian regime, Hizbullah has reportedly adopted a strategy of subversion against the al-Sharaa government—an issue with explosive potential for bilateral relations. Former Assad loyalists who did not flee to Moscow, Africa, or Venezuela now reportedly operate with relative freedom in Lebanon, using it as a base to monitor or harass the new Syrian authorities. Lebanese General Wahbi Katisha has claimed that Venezuelan President Nicolás Maduro provided 10,000 passports to Hizbullah for distribution among Syrian opponents of al-Sharaa.

These figures are reportedly visible in Hizbullah-controlled or Shiite-majority areas such as Baalbek, Hermel, Akkar, and the southern suburbs of Beirut (Dahieh), but also in Christian regions such as Kesrouane and Sunni-adjacent areas near Tripoli. They benefit from a protective environment in which they plan activities inside Syria.

According to press reports, many are former officers of the notorious Fourth Division led by Maher al-Assad, while financing allegedly comes from Assad’s cousin Rami Makhlouf. Another key figure is General Ghayass al-Dala, a former commander in the 25th Division, who led the failed rebellion in Latakia in April 2025.

Media reports claim that opposition forces to al-Sharaa number more than 168,000 armed fighters. This presence has triggered a Syrian response. Damascus has reportedly dispatched intelligence advisers to Lebanon to neutralize dissidents. Lebanese Army raids in Shiite areas have yielded limited results.

By late December 2025, Syria initiated a cycle of covert violence, drawing Lebanon into retaliatory dynamics between Syrian rebels and Hizbullah. Several former Syrian National Defense Force commanders were allegedly abducted from Lebanese coastal towns and forcibly returned to Syria. These operations suggest that Syrian intelligence is active in Lebanon, bypassing formal channels.

The Sukhni Case and the Shadow War

One of the most prominent cases is that of Ghassan Naassan al-Sukhni, whose body was discovered on December 23, 2025, in Kesrouane—an unusual location for an Alawite Syrian officer. Sukhni was a former senior Syrian intelligence officer and close aide to Major General Suhail al-Hassan (“The Tiger”), commander of the elite Tiger Forces (later the 25th Special Mission Forces Division). He fled to Lebanon after the regime’s collapse in December 2024.

Although the Lebanese Army officially classified his killing as a financial dispute and arrested a Syrian suspect, analysts and the Syrian Observatory for Human Rights point to political motives. Sukhni was allegedly part of the “Assadist Underground” in Lebanon—a network of former Tiger Forces officers attempting to rebuild influence, monitor pro-Sharaa elements, and plan destabilization activities in Syria’s coastal regions.

His killing is widely seen as the first high-profile purge of Assad-era figures on Lebanese soil. Whether conducted by Syrian intelligence or local actors, it signals that Lebanon is no longer a safe haven for the former regime’s security apparatus. Damascus has renewed demands for Lebanon to hand over approximately 300 former officers, whom it considers war criminals and national security threats.

The Lebanese state now faces a dilemma: shielding these figures risks a breakdown in relations with Syria, while extraditing them risks domestic backlash and international pressure, particularly from France, which has sought some of the same individuals for war crimes prosecutions.

Conclusion

The mounting tension between Lebanon and Syria reflects the friction of two states engaging as equals for the first time in half a century. While this new relationship is legalistic and complex—unlike the era of Syrian dominance—it carries a real risk of sporadic violence. Syria has made clear that it will not tolerate threats to its national security emanating from Lebanese territory.

The May 2026 parliamentary elections are widely viewed as a reset point. Unlike past elections, when Damascus effectively selected winners, the current contest reflects adaptation to a Syria that is no longer a patron but an assertive neighbor.

Where candidates once positioned themselves as either pro- or anti-Syria, new alignments are emerging. Sunni blocs, marginalized under the Assad-Hizbullah axis, now present themselves as natural partners to the al-Sharaa government. Parties such as the Lebanese Forces and the Free Patriotic Movement are competing to appear toughest on refugee returns, advocating strict deadlines for camp closures regardless of international pressure.

Hizbullah enters the 2026 elections in its weakest position in decades. Deprived of Syrian backing, it must campaign on a purely domestic platform focused on reconstruction and resistance. Analysts suggest that if Hizbullah and its allies lose their blocking third in parliament, the next government may formalize the border and ratify the Judicial Cooperation Agreement with Syria—steps Hizbullah previously obstructed to preserve its cross-border networks.

FAQ
Why has the Lebanon–Syria relationship changed so dramatically?
The collapse of Syria’s previous ruling system and the rise of a new transitional government reversed decades of power imbalance, forcing both states to renegotiate their relationship without a clear hierarchy.
What role do Syrian refugees play in current tensions?
Large-scale refugee returns have eased political pressure in Lebanon but created labor shortages, while Syria has used repatriation as leverage in broader diplomatic and security negotiations.
Why are Syrian prisoners in Lebanon such a contentious issue?
Lebanon views many detainees as security threats involved in terrorism, while Syria considers them political actors or revolutionaries, making prisoner transfers a major obstacle to normalization.
How has border security shifted since the regime change in Syria?
Arms smuggling routes have reversed direction, with Syria attempting to cut off supply lines to non-state actors, leading to clashes, stricter border controls, and accusations of non-cooperation.
How do Lebanese elections affect bilateral relations?
Political factions are repositioning themselves in response to a more assertive Syria, with election outcomes likely to determine whether formal agreements on borders, prisoners, and security cooperation move forward.

Col. (ret.) Dr. Jacques Neriah

Col. (ret.) Dr. Jacques Neriah, a special analyst for the Middle East at the Jerusalem Center for Security and Foreign Affairs, was formerly Foreign Policy Advisor to Prime Minister Yitzhak Rabin and Deputy Head for Assessment of Israeli Military Intelligence.
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