The Red-Hot Blue Line

The first weekend of 2024 saw one of the fiercest exchanges of fire between Hezbollah and Israel since the 2006 war. On January 6, the group launched antitank guided missiles, attack drones, and no less than sixty-two rockets against Israel’s northern air control unit in Mount Meron, causing some damage. Hezbollah described the salvo as an “initial response” to the targeted killing of senior Hamas official Saleh al-Arouri in Beirut days earlier. In response, the Israel Defense Forces struck Hezbollah military compounds, a surface-to-air missile unit, and other targets at seven sites in south Lebanon. On January 8, an IDF strike killed Wissam al-Tawil, a senior commander in the group’s Radwan special forces. The next day, Hezbollah drones attacked the IDF’s northern command headquarters, while Israel killed the head of the group’s southern aerial unit and three of his team. In all, Hezbollah has claimed ten new “martyrs” since Saturday.

Amid the fighting, Prime Minister Binyamin Netanyahu has restated Israel’s “resolve to return the northern communities home, diplomatically if possible; otherwise, by other means.” Similarly, Defense Minister Yoav Gallant told U.S. envoy Amos Hochstein, “We prefer the path of an agreed-upon diplomatic settlement, but we are getting close to the point where the hourglass will turn over.” Senior U.S. and European officials are now shuttling between Beirut and Jerusalem in a bid to stop the escalation. What exactly will it take to prevent a war in Lebanon and possibly beyond?

Blue Line Escalation Since October

A day after Hamas’s October 7 massacre, Hezbollah began attacking across the Blue Line, the UN-drawn provisional border between Israel and Lebanon. The group’s stated purpose was to show solidarity with Hamas and pin some IDF forces down so that they could not aid the Gaza fight. As of January 5, Hezbollah had acknowledged carrying out 670 attacks against Israeli military targets and villages, an average of seven per day (for details on all these attacks, see The Washington Institute’s interactive tracking map). The group has lost 159 “martyrs” in the process, including several killed in Syria. The toll in Lebanon also includes 16 Hamas and Palestinian Islamic Jihad terrorists, 35 civilians, and 1 Lebanese Armed Forces (LAF) soldier killed unintentionally.

Israel has lost 9 soldiers and 4 civilians to Hezbollah attacks, but the group has mainly boasted about another accomplishment—forcing around 80,000 Israelis to evacuate from a five-kilometer strip along the border. After witnessing hundreds of their houses and farms take damage, most of these evacuees are unwilling to return home until the threat is removed. Similarly, about 100,000 Lebanese have fled their villages in the south.

Following the 2006 war, the UN Security Council adopted Resolution 1701, which sought to prevent another conflict by mandating that the entire area south of the Litani River be made “free of any armed personnel, assets, and weapons other than those of the Government of Lebanon and [the UN Interim Force in Lebanon, or UNIFIL].” Instead, Hezbollah has spent the intervening years building up for the next war in several ways: by increasing the volume, range, lethality, and precision of its arsenal; establishing a massive ground assault capability on the Blue Line; demonstrating this capability through exercises that simulated breaching border obstacles and taking hostages; acquiring air defense capabilities that seemingly led Israel to decrease its air operations; digging cross-border attack tunnels that Israel destroyed in 2018 to prevent a massive surprise invasion; and a staggering number of other documented violations.

Indeed, Hezbollah’s array of forces and tactics on the Blue Line were the model for Hamas’s October 7 offensive. Israel therefore took quick action to prevent Radwan units from attempting their own assault, reinforcing northern units and evacuating border communities early in the war. The IDF was even reportedly on the brink of launching a preventive offensive against Hezbollah on October 11 but decided to focus on Gaza instead.

Although stopping Hezbollah attacks has historically been a bilateral issue between Israel and Lebanon, it is now a multilateral problem. The group has vowed to continue attacking as long as the fighting in Gaza persists, and Palestinian factions are using Lebanese territory to strike Israel with Hezbollah’s permission—as illustrated by Arouri’s presence in the group’s Dahiya stronghold upon his death.

More important, Israel may no longer be willing to keep living under such a severe military threat now that the pillars of its national defense—deterrence and early warning—failed so resoundingly. Consider this: Hamas’s massive opening barrage on October 7 involved launching 2,000 rockets in just ten minutes, partially overwhelming Israel’s defenses in some locations. Yet Hezbollah’s arsenal is ten times bigger than Hamas’s and includes precision missiles, giving it a first-strike capability that could seek to paralyze Israel’s air defenses and critical warfighting capabilities ahead of a ground and fire offensive. Accordingly, Israel may need to put preemptive military options back on the table.

The Limits of Israel’s Current Military Approach

Removing the direct fire threat entails pushing Hezbollah away from the border—at least beyond the range of its current antitank weapons (around five to ten kilometers), but possibly deeper. Yet pursuing that goal through massive IDF strikes could precipitate a wider war in which Hezbollah uses its 150,000 rockets and missiles to hit far inside Israel. Moreover, Jerusalem’s vital U.S. ally strongly objects to such expansion for fear of regional escalation. The IDF is therefore pursuing more limited options for now.

In the early days of the Gaza war, the IDF responded to Hezbollah attacks with immediate counter-fire operations that soon morphed into “lethal defense”—that is, attacking enemy forces before they attacked Israel. These responses later became more proactive, with Israel maintaining escalation superiority while using the daily exchange of fire to advance its goals. Specifically, Israeli operations have focused on degrading and destroying Hezbollah’s border positions and assets, including observation posts, launch sites, command posts, weapons caches, drones, air defenses, reconnaissance positions, military compounds, and sites run by the group’s fake environmental NGO Green Without Borders. These strikes have gradually increased in scope, depth, and quality, moving from outdoor targets to the outskirts of villages and finally inside them. Some high-value targets have also been struck north of the Litani.

Israel’s operations have spurred the group to pull some of its most capable Radwan forces from the border. After the IDF bolstered its northern defenses and hit dozens of Radwan assets along the frontier, Hezbollah leaders apparently reconsidered the value and cost of maintaining such a large forward deployment ready to strike Israel on short notice. Yet safely returning Israelis to their homes in the north would require a wider-scale Hezbollah retreat or removal, which can only happen under two circumstances: if the group is convinced to voluntarily withdraw, or if the IDF launches a larger offensive that runs a high risk of full-scale war.

The Diplomatic Track

To avoid further escalation, allied officials are pursuing a pair of diplomatic options: implementing Resolution 1701 and reaching a land border deal between Israel and Lebanon. On the first track, the United States and France have proposed a larger role for the LAF and UNIFIL near the Blue Line, reasserting Lebanese sovereignty with international support. Yet both of these entities have repeatedly failed to prevent or even adequately investigate Hezbollah violations, so putting them in charge of implementation would go nowhere under the current circumstances. The root causes of the resolution’s failure need to be addressed first: namely, Lebanese government and LAF collusion with Hezbollah, the group’s aggressive undermining of UNIFIL’s mission, and the UN’s acquiescence to these ongoing infringements. Hence, the burden of changing the status quo is now on individual countries working in concert rather than the UN.

The land border track was reportedly raised by Washington as a way to ease tensions and incentivize Hezbollah to move its forces northward, building on the success of the 2022 maritime border talks. By settling Lebanon’s claims over thirteen disputed “reservation” points along the Blue Line, Hezbollah would supposedly lose its pretext for fighting Israel and fielding its own army. Yet the Gaza war shows that Hezbollah has no qualms about attacking Israel for reasons that have nothing to do with the border. New talks could also exacerbate tensions rather than easing them, as seen when Hezbollah threatened Israel with war and launched drones toward its natural gas facilities during the maritime talks. More broadly, discussing border issues outside the context of a (currently unreachable) comprehensive peace deal could further undermine the integrity of the Blue Line and invite additional Lebanese disputes.

For example, Speaker of Parliament Nabih Berri recently reemphasized Lebanon’s commitment to Resolution 1701 but noted that implementation must begin with Israel halting its “aggression” and withdrawing from “all occupied Lebanese soil.” Similarly, Foreign Minister Abdallah Bou Habib declared that Israel must return to the Green Line (i.e., the 1949 armistice line), which would mean withdrawing from the Shebaa Farms, northern Ghajar, and the westernmost B1 point. Evidently, Lebanon’s stated commitment to 1701 is always a future prospect, conditioned on its own terms being fully met.

More important, rewarding Hezbollah’s aggression by making such concessions in the near term would only encourage more violations in the future. Under the current proposals, Israel is seemingly being asked to make serious border concessions in exchange for little more than easily reversible Hezbollah troop movements.

Given these challenges, diplomacy will likely deliver partial results at best. If so, Israel will need to consider unilateral military efforts until Hezbollah withdraws its forces from the Blue Line, whether in full or just the Radwan units. Yet all of the IDF’s military options—from continuing the current “degrade and dissuade” strikes to opening a massive offensive—would disrupt the calm needed for border residents to return home. Israel’s calculus will also be shaped by its numerous other deep challenges—not just the Gaza war and associated U.S. pressure, but also a simmering West Bank, militia threats in Yemen and Iraq, a looming nuclear Iran, growing economic disruption, reputational challenges abroad, and the same domestic political crisis that emboldened Hamas to attack.

Policy Implications

The international community has long chosen to sidestep the consequences of Hezbollah’s buildup, Iran’s massive support, and Beirut’s collusion. Yet after three months of watching the Blue Line burn, officials must now revisit past recommendations and offer urgent, realistic answers beyond just talking points. The United States, France, and Britain are best situated to help Israel, Lebanon, and their regional partners exhaust the diplomatic options for preventing war. They would be wise to focus on the following crucial steps:

• Stop Hezbollah’s violations while avoiding the pitfalls of false remedies and disingenuous Lebanese politics.
• Put comprehensive pressure on Iran and Hezbollah, including international designations, legal/financial sanctions, criminal enforcement, and efforts to curtail the global logistical networks that help move funds and arms from Tehran to Beirut.
• Hold top officials in the Lebanese government and LAF accountable for violating Resolution 1701 and colluding with Hezbollah. Many foreign defense officials still regard the LAF as Lebanon’s only hope, but in reality the force has become part of the problem. Future aid to the country’s civil and military institutions must be based on how well they uphold 1701, protect peacekeepers from Hezbollah, and enable UNIFIL’s freedom of movement.
• Enforce the arms embargoes mandated in Resolutions 1701 and 1559, with a particular focus on stopping the flow of Iranian weapons to Hezbollah. This means reviving relevant arms resolutions frozen by the 2015 nuclear deal.
• Give UNIFIL an active role in promoting and monitoring a demilitarized zone in south Lebanon, beginning with honest reporting about the situation on the ground.
• Tailor UNIFIL’s size to its actual mission, or vice versa. Its current activities on the ground do not justify having 10,000 troops in harm’s way and a $500 million yearly budget.
• Renew UNIFIL’s mandate in six-month increments only, ensuring that the Security Council can conduct more frequent reviews befitting the pace of events on the Blue Line.

All of these issues need to be addressed immediately, with the goal of correcting a course that has gradually taken Lebanon toward the abyss. Waiting for the yearly UNIFIL mandate talks in August may be too late. In the meantime, Israel will no doubt continue countering Hezbollah’s aggression and creating the conditions for the safe return of its border communities—while concurrently preparing for war should all other options fail, as they well might.

Brig. Gen. Assaf Orion (Res.) is The Washington Institute’s Rueven International Fellow and former head of the Israel Defense Forces Strategic Planning Division.