The Coming Conflict with Hezbollah

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The Issue

Although the Israel-Hamas war in Gaza has captured the world’s attention, there is a serious risk of war between Israel and Hezbollah, according to a new assessment by CSIS. Since October 7, 2023, there have been over 4,400 rocket, missile, and other stand-off attacks by Israel and Hezbollah combined. Hezbollah has also repeatedly violated UN Security Council Resolution 1701 by deploying forces and firing anti-tank guided missiles and other stand-off weapons against Israel from the zone between the Blue Line and the Litani River, according to CSIS geolocation analysis. The United States needs to increase its diplomatic engagement to prevent what could become a much wider and more violent war in the Middle East.

Introduction

Shortly after Hamas’s brutal terrorist attacks in southern Israel on October 7, 2023, Israel nearly launched a preventive war against Hezbollah in southern Lebanon. Israeli intelligence assessed that Hezbollah fighters were on the verge of crossing the border into northern Israel as part of a multi-pronged attack. The Israel Defense Forces (IDF) deployed fighter aircraft that awaited orders to strike targets in Lebanon. Israeli officials apparently notified the White House around 6:30 a.m. on October 11, 2023, that they were considering preventive strikes and requested U.S. support. But senior U.S. officials, including President Joe Biden, pushed back. According to CSIS interviews with U.S. officials, they were worried that Israeli strikes in Lebanon would unnecessarily trigger a regional war and were skeptical of Israel’s intelligence that an attack was imminent.[1]

Although Israel did not launch a preventive war, the possibility of an Israel-Hezbollah conflict looms over the region. Israel faces a dilemma. It can risk war with Hezbollah, but in the process, a war would broaden the fighting in a way that makes the current war in Gaza look like a minor dust-up. Israel could also wait, which would avoid war now with Hezbollah, but this could risk a more serious conflict in the future with a foe that is better armed and capable and that could control the timing of a war to its advantage.

To better understand the prospects of war, this brief asks several questions. What factors shape the possibility of war? What are Hezbollah’s capabilities today? What are Israel’s options? What options does the United States have to mitigate or prevent a war?

To answer these questions, this analysis includes a mixture of both quantitative and qualitative information. It compiles data on Israeli and Hezbollah strikes along the Israel-Lebanon-Syria border, geolocates Hezbollah attacks against Israel in the zone between the Blue Line and the Litani River, and examines satellite imagery of Israeli strikes against Hezbollah targets. It also assesses Hezbollah’s military capabilities, including compiling data on Hezbollah’s stockpile of 120,000 to 200,000 short-range guided ballistic missiles, short- and intermediate-range unguided ballistic missiles, and short- and long-range unguided rockets. Finally, it draws on interviews the authors conducted with U.S. and Israeli officials on a trip to Israel.

The analysis makes three main arguments. First, the security situation has dramatically worsened in recent months for several reasons: the October 7 attacks profoundly increased Israeli insecurity; the displacement of over 150,000 civilians on both sides of the Israel-Lebanon border has created growing pressure, particularly in Israel, to alter the security situation so that civilians can return; Hezbollah and Iranian-linked groups in Lebanon and Syria continue to stockpile stand-off weapons that can hit Israel; and Hezbollah continues to violate UN Security Council Resolution (UNSCR) 1701. Taken together, these factors have created a volatile situation in an already tense Middle East.

Second, violence between Israel and Hezbollah has already started to climb after nearly two decades of low-level conflict. Since October 7, there have been more than 4,400 violent incidents concentrated around the Blue Line and the Golan Heights involving Israel and Hezbollah, according to CSIS analysis. In addition, CSIS analysis indicates that Hezbollah’s anti-tank guided missiles (ATGMs) have struck Israeli forces from concealed launch sites less than three kilometers from the Blue Line on at least 17 occasions since October 7, a clear violation of UNSCR 1701.

Third, the United States needs to increase diplomatic efforts to prevent an all-out war, which would be devastating for both Lebanon and Israel and ignite a broader conflagration in an already combustible region, including triggering more attacks on U.S. forces.

The rest of this brief is divided into four sections. The first examines the evolving security landscape. The second section assesses Hezbollah’s capabilities and force disposition, particularly along the Israel-Lebanon border. The third section analyzes Israel’s objectives and options. The fourth section explores U.S. policy options.

The Changing Security Landscape

Israel has repeatedly fought Hezbollah since the group’s inception in the early 1980s. Indeed, Hezbollah has defined itself from the start in opposition to Israel and dedicated itself to driving Israel out of Lebanon. Israel and Hezbollah conducted periodic operations against each other in the 1980s and 1990s despite the presence of the United Nations Interim Force in Lebanon (UNIFIL), and Hezbollah succeeded in forcing the Israeli military to withdraw from Lebanon in 2000.[2] In the process, Hezbollah conducted an array of terrorist attacks against Israel around the world.

Despite Israel’s withdrawal from Lebanon, Hezbollah continued occasional attacks on Israel, using the pretext that Israel occupied Shebaa Farms, a small area at the intersection of the Lebanon-Syria-Israel border. Hezbollah claimed Shebaa Farms was Lebanese territory and thus that Israel’s occupation continued, despite the United Nations concluding that Shebaa Farms is Syrian and that Israel had evacuated its forces from Lebanon completely.[3]

Another area of dispute was the village of Ghajar, just west of Shebaa Farms and bisected by the Israel-Lebanon border. Its residents have both Lebanese and Israeli citizenship.[4] For years, a fence divided Ghajar, but Israeli forces reoccupied all of Ghajar in 2006 and today retain control there.

The low-level conflict between Israel and Hezbollah flared into an all-out war in 2006 after a Hezbollah cross-border kidnapping operation. The war left over 100 Israelis and around 500 Hezbollah fighters dead, as well as devastated Lebanon. Hezbollah likely did not anticipate its operation would spark an all-out war, and Hezbollah leader Hassan Nasrallah later announced that he would not have conducted the operation if he had known a war would occur.[5] Although Hezbollah suffered far more dead, some Israelis saw the war as a disaster due to the large number of Israelis killed, and the IDF’s battlefield performance was widely criticized.[6]

The 2006 war ended with UNSCR 1701, which created a zone between the Blue Line and the Litani River along the borders of Israel, Lebanon, and Syria. According to UNSCR 1701, the area between the Blue Line and the Litani River should be free from any armed personnel, assets, and weapons except for those of the government of Lebanon and UNIFIL.[7]

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Seth G. Jones
Senior Vice President; Harold Brown Chair; and Director, International Security Program
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Daniel Byman
Senior Fellow, Warfare, Irregular Threats, and Terrorism Program
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Alexander Palmer
Associate Fellow, Warfare, Irregular Threats, and Terrorism Program
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Riley McCabe
Program Manager and Research Associate, Warfare, Irregular Threats, and Terrorism Program
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After 2006, an uneasy deterrence prevailed. Israel occasionally attacked Hezbollah fighters and Iranian arms shipments headed to Hezbollah and other groups in Syria, and there were intermittent rockets, drones, and other stand-off attacks back and forth across the border. For the most part, however, the border was the calmest it had been in decades, with both sides eager to avoid another all-out war.[8]

Today, however, the situation is delicate for several reasons. First, the October 7 attacks dramatically increased Israeli insecurity. It is difficult for most outsiders to fully comprehend the psychological impact and trauma caused by the gruesome attacks. Israel was surprised on October 6, 1973, when Egypt and Syria launched an attack on Israeli forces in the Sinai and Golan Heights. But October 7, 2024, was largely a surprise attack that killed Israeli civilians, including women, children, and the elderly, and involved numerous atrocities and sexual violence, much of it captured on video. Indeed, it was the third-deadliest terrorist attack around the globe since the University of Maryland began collecting terrorism data in 1970, and on a per capita basis, it was 15 times more deadly than the terrorist attacks in the United States on September 11, 2001.[9] In interviews conducted by several of the authors in Israel in December 2023, Israelis of all sorts stressed the failure of their intelligence services and military forces on October 7, and many Israelis felt they could no longer rely on deterrence given its failure against Hamas on October 7.

The attacks took a psychological toll on Israelis. According to an analysis published in the medical journal The Lancet, the attacks led to notably higher levels of post-traumatic stress disorder (PTSD), depression, and generalized anxiety disorder (GAD) among Israeli citizens. It concluded, “Our findings show that the deleterious effects of these attacks were not restricted to those directly exposed to the brutal acts of terror but also to those indirectly exposed. Thus, these attacks are to be considered as a mass trauma event affecting an unprecedented proportion of the country/s population.”[10] According to a Gallup opinion poll, Israelis’ emotional health plummeted after the attack, with record-high majorities saying they experienced higher-than-normal levels of worry (67 percent), stress (62 percent), and sadness (51 percent). As Gallup concluded, “No other country has ever seen such a large year-on-year increase in negative experiences.”[11]

Consequently, Israel’s risk tolerance has likely changed. If Hamas, less well-armed and trained than Hezbollah, can brutally kill over 1,100 Israelis, what might the more formidable Hezbollah do? Hezbollah’s close relationship with Iran and its ties to Hamas reinforce this fear. Reducing the risk Hezbollah poses includes ensuring that Hezbollah’s elite Radwan forces are not poised on Israel’s border, as they were before October 7, 2023. Israel would also like curbs on Hezbollah’s arms and other, more expansive restrictions, though they are aware this is unlikely. Israeli officials profess to prefer a diplomatic solution but warn that “we will have to act on our own” should diplomacy fail.[12]

Second, in addition to increasing Israel’s sense of insecurity, the repercussions of the October 7 attack and clashes between Hezbollah and Israel have displaced more than 150,000 people on both sides of the Israel-Lebanon border since October 2023, including roughly 80,000 civilians from northern Israel and 75,000 from southern Lebanon.[13] For Israel, resettling its internally displaced persons back to their homes and villages in northern Israel will require creating—and ensuring—a security environment that currently does not exist. Israeli leaders need to convince their population that, this time, the intelligence services can anticipate any attack and the military can stop it—a difficult task given Hezbollah’s capabilities and one far harder due to the discrediting of military and intelligence officials on October 7. Domestic pressure has been growing to improve the security situation. According to Avigdor Liberman, a former minister of finance who leads an opposition party, the Israeli government has been weak in the north: “The red line became a white flag—the war cabinet surrendered to Hezbollah and lost the north.”[14]

Third, Hezbollah has dramatically improved its military since 2006 and stockpiled over 120,000 stand-off weapons in Lebanon and Syria, as discussed in more detail in the next section. With Iranian partner and proxy forces active in Lebanon, Syria, Iraq, and other countries across the region, the threat from the north could get worse over time, not better.

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Fourth, Hezbollah has repeatedly violated UNSCR 1701 by stationing its forces in the zone between the Blue Line and the Litani River, sometimes under the cover of the fake nongovernmental organization “Green Without Borders.” Geolocated footage from Hezbollah propaganda videos indicates that Hezbollah ATGMs have struck Israeli forces from concealed launch sites less than five kilometers from the Blue Line on at least 17 occasions since October 7, as shown in Figure 2, a clear violation of UNSCR 1701.[15] These attacks have mostly been against Israeli military bases and intelligence, surveillance, and reconnaissance (ISR) systems. At least seven Israeli civilians and approximately 10 IDF soldiers have been killed in the attacks.[16] ATGMs played a major role in the 2006 war, during which they accounted for the majority of Israeli infantry casualties, including the loss of 24 tank crewmen and penetration of about 20 tanks.[17]

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As shown in Figure 3, there was little fighting between Hezbollah and Israel in the months prior to the October 7 attack. But the 15 weeks after the attack have witnessed more than 4,400 violent incidents involving Israel and Hezbollah. Hezbollah began to launch limited attacks on Israel as a way of showing solidarity with Hamas. This led to an Israeli response, resulting in a bloody tit-for-tat. As Hezbollah leader Hassan Nasrallah warned, “You expand, we expand. You escalate, we escalate.”[18] The incidents have been concentrated around the Blue Line, as illustrated in Figure 4.

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Hezbollah’s Objectives, Military Forces and Capabilities

This section examines Hezbollah’s overall objectives, force design, defensive positions, rocket, missile, and unmanned aircraft system (UAS) arsenal, anti-tank capabilities, air defense capabilities, and proficiency as a fighting force.

Objectives: Hezbollah has several objectives that could lead to a conflict with Israel, though the organization has numerous, and at times competing, goals, some of which make a conflict less likely or at least would lead Hezbollah to be cautious. Hezbollah sees itself as a revolutionary organization that is one of the leaders of the broader Muslim struggle against Israel. Destroying Israel has been a part of its core ideology since its founding, and most of its members are sincerely against the very existence of the Jewish state. Hezbollah shares this goal with Iran, which also rejects Israel ideologically and sees it as a threat to the Islamic Republic: for decades, Iran and Israel have engaged in a shadow war, with Israel conducting assassinations against Iran and building alliances with regional rivals of the Islamic Republic like Saudi Arabia. Iran, for its part, has backed groups like Hamas and Hezbollah against Israel, used terrorism, and otherwise tried to weaken Israel. Hezbollah also sees itself as the defender of Lebanon, and various territorial disputes and Israeli incursions are a constant source of tension. Finally, Hezbollah, like Hamas, seeks the release of prisoners in Israeli custody.

Hezbollah, however, has important reasons for caution. Most importantly, Hezbollah seeks broader popularity in Lebanon, and triggering a destructive war could grievously undermine support, particularly outside its Shiite core constituency. Iran also may seek to keep Hezbollah in reserve as a weapon to use should Israel or the United States launch a major attack on Iran itself. Finally, Hezbollah recognizes the military power of Israel and would not lightly provoke a conflict it might lose or, at the very least, lead to widespread destruction in Lebanon.

Force Design: Hezbollah has approximately 30,000 active fighters and up to 20,000 reserves.[19] Its forces primarily consist of light infantry, which have historically been trained and built for stealth, mobility, and autonomy. Hezbollah has employed a version of what the United States calls “mission command,” empowering subordinates to make independent battlefield decisions based on a commander’s intent.[20] This force design has allowed Hezbollah to operate effectively under conditions of overwhelming Israeli firepower.[21] In 2006, for example, its rocket units were designed to set up a launch site, fire, and disperse in less than 28 seconds, relying on prepositioned equipment, underground shelters, and mountain bicycles to achieve such a small window of exposure.[22] In the wake of the 2006 war, Hezbollah continued to build on the strengths of this approach, decentralizing its command and control and reorganizing to force the IDF into more urbanized terrain where its fighters can take advantage of concealed, fortified positions.[23]

Hezbollah’s experience fighting in support of Bashar al-Assad in Syria for the past decade has given it access to capabilities and competencies used by conventional armies. Hezbollah can now conduct coordinated maneuvers of larger forces, employ suppressive artillery, and conduct logistics to support larger groupings of forces.[24] Fighting in Syria has also given Hezbollah access to T-72, T-54/-55, and T-62 main battle tanks (MBTs).[25] Its ability to employ armor inside Lebanon, however, is questionable. MBTs require dedicated sustainment formations and supply chains that may not exist in Hezbollah’s areas of control in Lebanon itself, and Israel would aggressively target MBTs with fighter aircraft, drones, and artillery. Hezbollah also fought against a different enemy in Syria—irregular forces that look very different from the modern military of the IDF. Hezbollah’s ability to effectively employ the capabilities it has gained since 2006 in the face of IDF firepower, especially airpower, is also unclear, and indeed, it is likely that any large, heavy forces would be quickly destroyed if they were deployed.

Geography and Defensive Positions: The geography of southern Lebanon offers several advantages that Hezbollah fighters could exploit in a war with Israel. The region, including much of the area directly across the Israeli border, predominantly consists of rocky hills. In 2006 and in other clashes with Israel, small and mobile groups of Hezbollah militants used trees, patches of vegetation, caves, surface irregularities, and buildings along the slopes of the hills to conceal their movements and fire rockets, UASs, and ATGMs at Israeli positions on the border. Any heavy Israeli military ground force attempting to move throughout the region would likely be restricted to the major hard-packed roadways due to the hilly terrain and would, therefore, be vulnerable to harassment with ATGMs, improvised explosive devices (IEDs), and ambushes.

Hezbollah has built a network of tunnels and bunkers in the hills of southern Lebanon to host and move equipment and personnel relatively securely.[26] Hezbollah also uses this infrastructure to launch ambushes and rocket attacks. Where it lacks purpose-built military fortifications, Hezbollah fighters can exploit existing civilian infrastructure in the cities, towns, and villages throughout the region. During the 2006 war, civilian infrastructure was critical to Hezbollah fighters in southern Lebanon. They used it in place of formal military fortifications to hide command centers, complicate Israeli targeting, conceal fighters for ambushes, and enable fighters to disperse, maneuver, and defend in depth.[27] Thousands of civilians fled from southern Lebanon as strikes between Hezbollah and Israel intensified after October 7, 2023.[28] Some of the towns and villages along Lebanon’s southern border almost completely emptied.[29] In a war with Israel, Hezbollah could exploit civilian infrastructure and its network of tunnels and bunkers to attack Israeli ground forces and quickly retreat. Aware of Hezbollah’s fortifications and probable tactics, Israeli attacks would likely emphasize clearing and destroying Hezbollah’s tunnel network in southern Lebanon.

A number of rivers run through southern Lebanon, including the Litani River, which flows south from the Lebanon Mountains before bending west where it empties into the Mediterranean. Control of these rivers and their features represents an important strategic objective, including controlling the movement of troops, equipment, and supplies. These rivers also serve as natural defensive fortifications that can be exploited for tactical advantages in combat by defending forces.

Rockets, Missiles, and Unmanned Aerial Systems: Hezbollah’s rockets and missiles pose two distinct threats to Israel. The first is their coercive effect: continuous rocket, missile, and UAS barrages can kill or wound Israelis—both civilians and military personnel—or destroy important political or economic infrastructure in Israel. This is the way Hezbollah’s rockets and missiles were primarily used in 2006 and how they are usually discussed in the context of war with Israel.[30] The second threat comes from the tactical and operational effects of these systems: suppressing or attritting IDF forces to limit the effectiveness of Israeli operations. Hezbollah gained experience conducting combined arms operations in Syria, and the group may attempt to use rockets and missiles as part of ground operations against Israeli forces.

Hezbollah is probably the most heavily armed non-state group in the world, and its stockpiles of rockets, missiles, and UASs are a major part of its arsenal. Estimates of how many rockets and missiles Hezbollah possesses vary from 120,000 to 200,000.[31] Because of Hezbollah’s close relationship with Iran, it is likely that Tehran would resupply Hezbollah quickly if it used this arsenal in a conflict with Israel. This resupply is easier than in the past, as Iran’s presence in Syria expanded considerably after Tehran came to the rescue of the Syrian regime when civil war broke out after 2011, creating a land bridge that enables weapons to go from Iraq to Syria to Hezbollah in Lebanon. This stands in sharp contrast to Hamas, where weapons and people must be smuggled via tunnels from Gaza.

As shown in Table 1, the bulk of Hezbollah’s arsenal consists of short-range unguided projectiles. Hezbollah has also dramatically increased its access to long-range missiles since 2006, meaning that most of Israel will feel the threat of Hezbollah attacks if the conflict escalates. Finally, Hezbollah’s precision-guided missiles pose an acute threat to Israel’s most important political, military, and economic centers—a threat that did not exist in 2006.

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Eliminating the threat from Hezbollah’s rockets will be extremely difficult. The rockets can be launched from trucks, increasing their mobility and therefore survivability, or from underground bunkers, as was common during the 2006 war.[32] Finding and destroying Hezbollah’s rocket and missile capabilities would involve an enormous reconnaissance-strike effort involving a variety of intelligence assets, precision strike capabilities, and ground forces.

Hezbollah’s rocket and missile arsenal also includes long-range missiles. These are also likely to be used mainly in a coercive capacity, with Hezbollah undertaking long-range strikes against Israeli population centers to undermine Israeli support for the war. Hezbollah used its long-range rockets and missiles throughout the 2006 war despite an Israeli air campaign aimed at destroying their launchers and Hezbollah’s apparent unwillingness or inability to make much use of its Iranian-made long-range weapons.[33]

Hezbollah’s guided missiles make up an even smaller number of those long-range missiles—a few hundred at most.[34] The accuracy of these weapons makes each attack more devastating and creates greater pressure on Israeli air defense systems.[35] They provide Hezbollah with the capability to strike high-value targets, vital economic centers, and critical infrastructure.

While Hezbollah has historically used its rockets and missiles to impose pain on Israel rather than as part of combined arms operations, an important unknown is how Hezbollah might use its rocket and (to a lesser extent) missile capabilities in support of ground operations against the IDF. Hezbollah could attempt to capture territory in northern Israel or the Golan Heights in a Hezbollah-Israel war, or at least conduct raids there.[36] This would require ground maneuver, which modern militaries usually enable using suppressive fire from artillery or air platforms. Hezbollah demonstrated the ability to integrate ground maneuver with suppressive fires in Syria, and it may attempt to do so in a war with Israel. Such tactics are difficult in practice, and expertise is probably unevenly distributed across Hezbollah’s military forces. IDF air defenses and air power would also limit Hezbollah’s ability to use its rockets and missiles in this manner.

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In addition to its rocket and missile stockpiles, Hezbollah possesses a significant arsenal of UASs that include commercial quadcopters, suicide drones, loitering munitions, and more sophisticated platforms with surveillance and strike capabilities. Hezbollah’s UASs are almost entirely supplied by Iran and are used to conduct surveillance of—and strikes against —Israeli targets. On January 25, 2024, the IDF struck a 1,200-meter runway in southern Lebanon that it alleges Hezbollah built with Iranian assistance and was used by Hezbollah to launch large UASs. The airstrip and the surrounding base illustrate the advancement of Hezbollah’s UAS capabilities to include larger and more sophisticated systems. The base also contained a helicopter landing pad, support and storage facilities, and warehouses and UAS hangers under construction. The damage to the airstrip caused by the Israeli airstrikes can be seen in Figure 5, including four bomb craters on the runway.[37]

Since October 7, Hezbollah has attempted at least 40 UAS attacks against Israeli targets, as shown in Figure 6. Several of these attacks have successfully penetrated Israeli air defense systems, killing IDF soldiers and damaging military sites in precision strikes.[38]

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As seen in Table 2, Hezbollah UAS systems come in a wide variety. This list is not exhaustive, and Hezbollah likely possesses additional Iranian or indigenous drone models. Also not shown are the variety of commercial drones, such as Chinese DJI quadcopters, that Hezbollah possesses and which can be used to conduct surveillance or modified to deliver explosive payloads.[39] Should war with Israel break out, Hezbollah would likely receive additional imports of drones from Iran and emphasize adapting commercial off-the-shelf systems to their needs. After all, Iran has established logistics supply routes—both air and land bridges—that can bring weapon systems and other equipment from Iran to Lebanon through Iraq and Syria. The result is that Hezbollah would probably be able to sustain a campaign of UAS attacks against Israeli targets in Lebanon and Israel unless supply routes were cut.

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Hezbollah’s tactical employment of UASs in a war with Israel is difficult to predict. Hezbollah drone operators have received training from Iran’s Islamic Revolutionary Guard Corps–Quds Force, have performed military exercises with drones, and are observing the war in Ukraine, where a variety of new uses and techniques for drones on a battlefield have emerged.[40] Hezbollah could attempt to use its UASs as part of a reconnaissance-strike complex, relaying targeting information for indirect fires or attacking mobile Israeli targets, but Hezbollah’s ability to coordinate its UAS and ground-based capabilities remains to be seen. Hezbollah could also use UASs to detect, surveil, and attack Israeli forces should they enter southern Lebanon or to overwhelm Israeli air defenses through swarming attacks, possibly in combination with rockets and missiles. The effectiveness of these tactics will likely be limited, however, by Israel’s sophisticated counter-UAS capabilities, including electronic warfare systems, air defense systems, and other countermeasures that could disrupt UAS communications with ground systems or knock them out of the sky altogether.

Anti-tank Guided Missiles and Improvised Explosive Devices: ATGMs and IEDs give Hezbollah potent capabilities to attack armored vehicles and fortified locations. These capabilities were vital to its tactical successes in the 2006 war, although Israeli tactical failures contributed to the loss rate it experienced in 2006. The IDF is unlikely to repeat those mistakes.[41] 

Hezbollah has almost certainly improved its anti-tank capabilities since 2006. It currently fields an ATGM system, Tharallah, that is designed to overcome the active protection system used by the IDF’s Merkava MBTs, although its efficacy is unclear from open sources.[42] Hezbollah has taken steps to improve the mobility of its anti-tank units, mounting Kornet anti-tank missiles on all-terrain vehicles.[43] Several news outlets also reported in late January 2024 that Hezbollah had used a more advanced Kornet-EM to attack an Israeli air control base, which would represent a significant increase in ATGM range and destructive power.[44] On the tactical side, analysis of Hezbollah’s combat performance in Syria suggests that its members remain well schooled in using ATGMs against armored vehicles and fortified infantry positions.[45] The result is that Hezbollah’s ATGMs are likely to remain one of its deadliest capabilities, even if they do not attain the success rate of 2006.

Hezbollah also has a considerable IED capacity. Hezbollah employed IEDs with explosively formed penetrators (EFPs) against Israel in the 1990s and will almost certainly seek to do so again.[46] EFPs are shaped charges with a concave end, which typically send a molten copper slug through targets and then create a deadly spray of hot metal. Hezbollah’s expertise in using IEDs probably allowed it to contribute to IED attacks against U.S. and British forces in Iraq.[47] During the war in Iraq, Iran’s Islamic Revolutionary Guard Corps–Quds Force—which aids Hezbollah—built infrared triggers, explosive circuits, and other EFP components in Iran and smuggled them across the border in Iraq to be used against U.S. forces.[48] Hezbollah could also conduct attacks on Israeli forces using tunnel bombs, which were used in Iraq and Syria to literally undermine fortified positions, or improvised rocket-assisted munitions, which Hezbollah used.[49] These IED capabilities, combined with Hezbollah’s ATGMs, would allow the group to harass and disrupt the advance of Israeli ground forces in Lebanon.

These weapons, however, will not be decisive in battle. They are suited for killing one vehicle at a time or striking a small, fortified position, not for defeating a combined force integrating infantry, armor, indirect fires, and air power. Israeli countermeasures, such as the Trophy active protection system, will also limit their efficacy. IEDs will, however, inflict casualties, which Hezbollah leaders probably believe would undermine political will in Israel.

Air Defense: Since the 2006 war, Hezbollah has emphasized the advancement and expansion of its air defense capabilities in an effort to degrade Israeli air superiority.[50] Hezbollah’s air defenses include a range of systems primarily manufactured by Iran and Russia, including anti-aircraft guns, man-portable air defense systems (MANPADS), and short- and medium-range surface-to-air (SAM) missile systems, as seen in Table 3. These systems most commonly make their way into Lebanon smuggled through Syria, and Hezbollah has occasionally used them to engage Israeli UASs flying over southern Lebanon in recent years.[51]

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In November 2023, U.S. intelligence officials reportedly believed that Russia’s Wagner Group intended to transfer another SA-22 system to Hezbollah from Syria.[52] There have also been recent allegations that militias in Syria are actively training to use Iran’s most advanced air defense system, the Khordad-15.[53]

As shown in Figure 7, Israeli aerial activity has decreased in recent years and remains at historically low levels today, suggesting that Israel takes the threat of Hezbollah’s air defense systems to its aircraft seriously. Statements from Israeli military officials confirm as much. In 2022, the outgoing chief of Israel’s air force stated that Israel no longer had unimpeded air superiority over southern Lebanon.[54]

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In the event of war, Hezbollah’s air defenses would likely force Israeli aircraft to fly at higher altitudes, reducing their ability to accurately hit targets on the ground.[55] At the same time, Hezbollah’s air defense systems would be high-priority targets for Israel. On February 26, 2024, the IDF announced that it had struck Hezbollah’s air defense sites in the Beqaa Valley in response to Hezbollah shooting down an Israeli drone over Lebanon earlier that day.[56] In an escalated conflict, Israel would likely continue to favor the use of UASs over manned aircraft to reduce the risk posed by air defense systems to its pilots, though Israel does have fifth-generation aircraft such as the F-35 Lightning II stealth fighter. A successful downing by Hezbollah of a manned Israeli aircraft would be a strategically significant event.[57] Although Hezbollah’s upgraded air defense systems pose a greater threat to Israeli aircraft than they did in previous conflicts, Israel still has immense air superiority over Lebanon. Israel’s air force boasts some of the most advanced aircraft in the world, including U.S. and indigenously designed systems. Since the October 7 attack, Israel’s air force has successfully struck targets across Lebanon on almost a daily basis.

Human Factors: Hezbollah’s tactical proficiency, combat experience, and will to fight make it a much deadlier threat than Hamas—and even other regional militaries. Western analysts praised Hezbollah’s efficacy in the 2006 war with Israel, and its forces have only since grown more effective.[58] Hezbollah’s combat experience in Syria has given its troops experience in ground combat that few regional militaries possess, forcing them to learn how to conduct offensive operations and exposing them to the tactics, techniques, and procedures of the Russian military.[59] Hezbollah members have also repeatedly displayed a willingness to accept decisive engagement and fight to the last soldier—attitudes that will only be increased by the desire to defend their homes from an Israeli offensive.[60]

In short, the Hezbollah that Israel would face if violence were to escalate to major ground operations is more capable than in 2006. Hezbollah is larger, better armed, and more experienced, thanks in part to its experience fighting in Syria. It is most effectively designed to fight a coercive campaign aimed at killing Israeli soldiers and civilians at a steady rate through rocket, long-range missiles, ATGM, and UAS attacks. But it may also have some ability to conduct combined arms offensives against Israeli troops and limit Israeli air dominance. Even so, it remains technologically outmatched by the IDF, which has long prepared for a rematch of the 2006 war, has been engaged in a war with Hamas since October 2023, and will be able to bring much greater firepower to bear from its land- and air-based platforms.

Israeli Objectives and Options

In light of the changing strategic landscape and Hezbollah’s evolving capabilities, what options does Israel have? There are at least four options: (1) return to the pre–October 7 status quo and emphasize deterrence, (2) start an all-out war with Hezbollah to destroy the group’s capabilities and force it to comply with Israel’s demands, (3) engage in a limited war with Hezbollah to put pressure on the group and push its forces further from the Israeli border, and (4) use coercive diplomacy to better implement UNSCR 1701.

Option 1: The Status Quo Ante and a Return to Deterrence

Israel might try to return to a deterrent approach, which has uneasily kept the peace for almost 20 years. Deterring Hezbollah rests on the idea that the threat of war—including the potential destruction of portions of Lebanon—and punitive strikes on the group and Lebanese infrastructure will keep the group from launching attacks or at least massive strikes on Israel. This threat works by endangering something Hezbollah holds dear, such as the lives of its leaders, its power in Lebanon, and the well-being of its constituents. After Israel left Lebanon in 2000, it retaliated against the occasional rocket strike or other violation of the peace with the threat of more massive strikes should Hezbollah mount a larger attack. As Prime Minister Benjamin Netanyahu warned in December 2023, “If Hezbollah chooses to start an all-out war, then it will single-handedly turn Beirut and South Lebanon, not far from here, into Gaza and Khan Yunis.”[61]

Deterrence seems to be alive even after October 7. Nasrallah has stressed in public statements that Hezbollah does not plan a broader war even as it supports the Palestinians and will not rule out escalation if circumstances change.[62] Hezbollah strikes focus on a discreet target set along the border even though the group has the capacity to launch far more attacks and to strike all of Israel. It is clearly trying to limit its attacks even as it shows solidarity. Hezbollah cares about its constituents and recognizes that a repeat of the 2006 war, let alone something much worse, would be a disaster for these supporters. In recent years, Lebanon’s economy has plummeted, and Hezbollah does not want to take the blame for a war that would further devastate the country.[63] Israeli threats have made clear to Hezbollah that Lebanon would be hit hard if an all-out conflict resumes, and the devastation of Gaza reinforces the credibility of this threat.

Deterrence, however, could fail for several reasons. A strike that kills large numbers of Israeli civilians, even if accidental, would inflame the situation. Deterrence also rests on understanding an adversary’s decision calculus, and Israel might misunderstand Hezbollah’s tolerance for attacks on Hamas leaders or the continued loss of Hezbollah cadre, including important operational leaders. As previously noted, Israel’s risk tolerance has changed, and Israeli leaders might decide that even a small chance of Hezbollah attacking Israel needs to be preempted.

Option 2: An All-Out War

Should deterrence fail, whether by accident or by choice, an all-out war is possible. Israel’s chief of staff, Herzi Halevi, told Israeli soldiers that the chances of war against Hezbollah are growing.[64] Part of Israel’s logic is that a war with Hezbollah at some point is inevitable and that Israel should not wait for a surprise attack. Chuck Freilich, a former Israeli deputy national security adviser, noted, “If you believe that with Hezbollah is inevitable, as many in Israel do, then now is as good a time as any to do it.”[65]

A war would likely focus on preventing a more dangerous repeat of October 7, going after Hezbollah’s rocket, missile, and drone capabilities and trying to push the group’s fighters farther from the border, probably to the other side of the Litani River. Even a decisive defeat of Hezbollah, however, would not lead to the group’s destruction given its deep roots in Lebanon and strong support from Iran.

Israel possesses considerable capacity for war with Hezbollah, though the Lebanese group would be a formidable foe. Israeli intelligence tries to continuously monitor Hezbollah missile and UAS sites.[66] Indeed, part of why Hamas was able to surprise Israel on October 7 was likely because Israeli intelligence was more focused on Hezbollah, which it saw as the greater threat.[67]

The IDF outnumbers Hezbollah in troops, tanks, artillery, and other forms of military power. Israel’s equipment is also far more sophisticated, and its forces are better trained.[68] Since its poor performance in the 2006 war, Israel has prepared for war with Hezbollah, in contrast to its lack of preparation for the invasion of Gaza.[69] Israel has prepared a target set it can draw on at any time for strikes.[70]

An Israeli attack would probably involve massive airstrikes that would seek to target Hezbollah leaders, disrupt command and control (which would also involve cyberattacks), and hit Hezbollah’s rocket launcher sites, especially those that involve Hezbollah’s precision munitions arsenal.[71] Although Israel would target Hezbollah leadership and military sites in Beirut and in the Beqaa Valley, it would likely focus most of its effort on Hezbollah’s presence near the border. Using lessons learned in Gaza, Israel would likely also attempt to destroy Hezbollah’s tunnel network. Finding and targeting Hezbollah tunnels has been an Israeli military and intelligence priority for years, though Hezbollah showed in 2006 that it could successfully use deception to build an extensive network.[72]

Some Israeli leaders, such as Benny Gantz, a member of Prime Minister Netanyahu’s war cabinet, remarked in February 2024 that Israel could strike the Lebanese military as part of a broader war. “It is important that we be clear—the one responsible for the fire from Lebanon is not only Hezbollah or the terrorist elements that carry it out, but also the government of Lebanon and the Lebanese state that allows the shooting from its territory,” Gantz said. He also added: “There is no target or military infrastructure in the area of the north and Lebanon that is not in our sights.”[73]

Israel might then invade Lebanon with several divisions (it used four in Gaza, where the dense urban terrain required extensive manpower), seeking to uncover and destroy hidden tunnels and force Hezbollah fighters to the other side of the Litani River. Although southern Lebanon is not densely populated like Gaza, some of the fighting would involve urban warfare. If Israel were to successfully remove Hezbollah forces, it would then carefully monitor the area and conduct extensive strikes if necessary to prevent any return. Israel might push for a more robust UNIFIL force to monitor the area or seek to create a buffer zone, working with Lebanese proxies, as it did before 2000, though both of these approaches have proved insufficient in the past.

Hezbollah would respond in several ways. Hezbollah forces would conduct guerrilla attacks, likely using an extensive tunnel network and well-prepared defensive positions near the Israeli border, taking advantage of the rough terrain there. Hezbollah would also attempt cross-border attacks as well as perhaps maritime infiltration in order to strike at Israel directly. In addition, Hezbollah would use its massive rocket and missile arsenal to attack Israel, overwhelming Israel’s defensive systems and striking at targets throughout the entire country: in 2006, Hezbollah was able to conduct rocket and missile attacks for all 34 days of the war, and its arsenal today is far larger. Finally, Hezbollah might conduct international terrorist attacks at Israeli targets around the world, working extensively with Iran to do so. Hezbollah would also use its influence over the Lebanese government to ensure that any ceasefire was on its own terms.

Option 3: Limited War

Another approach is to continue the current level of conflict, in which there is no all-out war, but dozens of Hezbollah fighters are killed every month, as well as a small number of Israelis. Civilians would die on both sides, but if current patterns continue, far more Lebanese would be killed than Israelis. Limited war would involve regular Israeli airstrikes on Hezbollah forces near the border and on the occasional Hezbollah commander, while Hezbollah would fire anti-tank missiles at military and civilian infrastructure across the border, allow Palestinian groups based in Lebanon to attempt the occasional cross-border attack, and launch rocket and mortar attacks on Israeli positions.

Limited war would serve several purposes for both Israel and Hezbollah. For Israel, such strikes keep Hezbollah off balance, forcing its commanders to hide or risk being killed and putting its weapons caches at risk. In addition, the strikes show the Israeli people that the government is actively trying to defend them and make it hard for Hezbollah to amass forces that might conduct a surprise attack across the border. For Hezbollah, limited war allows it to show solidarity with Hamas and affirm Iran’s “resistance” agenda. Although Hezbollah has lost over 100 fighters since October 7, this level of casualties is manageable for a large organization with many skilled personnel. For both Hezbollah and Israel, limits to the conflict help avoid the costs of an all-out war.

At the same time, limited war poses problems for both groups, in addition to the regular casualties. The biggest problem is the impact on civilians along the border. The conflict worsens Lebanon’s always-simmering instability and mounting economic problems, and Hezbollah risks taking the blame. Perhaps 75,000 Lebanese have fled southern Lebanon, with no immediate prospect of return: a similar political problem for Hezbollah to what Israel faces, with its displaced citizens, who are unlikely to return to their homes en masse as long as limited war continues.[74] Finally, it is unclear whether a limited war would actually remain limited.

Option 4: Coercive Diplomacy

Another approach is to use coercive diplomacy to compel Hezbollah to abide by UNSCR 1701. To this end, the United States, often represented by mediator Amos Hochstein, is using diplomacy to negotiate with Lebanese leaders, and thus indirectly with Hezbollah, while Israel is putting military pressure on the group through a mix of strikes on Hezbollah forces and leaders. The renewed threat of an all-out war gives this pressure additional strength. Hezbollah, however, does not want to be seen as surrendering to Israeli pressure, particularly at a time when Israeli attacks on Palestinians are dominating the headlines.

In addition to ending Hezbollah attacks on Israel, the goal for Israel would be for Hezbollah to move its armed forces back, as promised under UNSCR 1701, to the Litani River. It is possible that Israel would also accept a less comprehensive withdrawal that moves Hezbollah farther back from the Israel-Lebanon border but not all the way to the Litani River. UNIFIL might need to be bolstered substantially and be far more aggressive in its use of force in response to any incursion, both of which would be difficult to accomplish.

Israel, too, would be asked to make concessions and changes in response to UNSCR 1701 and to appease Hezbollah. Israel regularly violates Lebanese airspace, which Israel does to strike and monitor Hezbollah positions.[75] Hezbollah would also likely seek an Israeli evacuation of Shebaa Farms and the village of Ghajar, perhaps placing them under UNIFIL so that the group could claim a political victory even as it made concessions.[76]

Managing the Crisis

With a high risk of conflict, Washington needs to step up efforts to prevent an all-out war (Option 2), which would have significant and negative implications for the United States at home, in the Middle East, and around the globe. Restoring deterrence (Option 1) and limited war (Option 3), while better from a U.S. perspective, both have their limits. Option 1 appears, at best, a temporary solution that could easily fall apart, while Option 3 could spiral into an all-out war and, even in limited form, could be disastrous for both Lebanon and Israel. The U.S. military is already overstretched in countering a range of threats, such as China in the Indo-Pacific, including around Taiwan and the South and East China Seas; North Korea, which is accelerating its conventional and nuclear capabilities and issuing provocative threats of nuclear conflict with South Korea; and Russia, which is waging an attrition war against Ukraine and developing land, air, naval, space, and cyber capabilities that threaten the United States and its allies. The U.S. defense industrial base is also overstretched.[77] An all-out war between Israel and Hezbollah would likely require additional U.S. military assets—such as one or more carrier strike groups as well as fixed-wing aircraft, ISR platforms, and munitions—that are needed in other theaters.

A war could dramatically raise tensions with populations across the Middle East and beyond—including in the United States and Europe—and lead to increased attacks by Iranian-backed groups against Israel, the United States, and commercial targets in the region and littoral areas. U.S. forces in the region, already facing limited attacks from Iranian-backed groups, would likely face more frequent and larger strikes. Although the economic implications of the Gaza war have been limited, an all-out war would likely have significant implications on trade, supply chains, energy prices (including oil and gas), investment, and tourism.[78]

A major war would also have significant humanitarian costs. Hezbollah’s rocket and missile systems put all of Israel under threat, and its ground forces are far more formidable than those of Hamas. Israel’s promise to devastate Hezbollah strongholds in Lebanon as it has in Gaza is credible, and thousands could die in these attacks. Lebanon’s economy, already under severe strain, could collapse completely as hundreds of thousands of people are displaced and the country’s infrastructure is destroyed.

Consequently, the United States should focus its efforts on implementing a policy of coercive diplomacy (Option 4). There has been some movement toward negotiations. For example, U.S. officials like Amos Hochstein have made energetic efforts to restore stability and discussed a proposal that calls for the withdrawal of non-state armed actors from southern Lebanon, a deployment of Lebanese armed forces, and a development plan for southern Lebanon.[79] In addition, France presented a three-step proposal to Israel, Lebanon’s government, and Hezbollah (and briefed it to the United States) that outlines a 10-day process of de-escalation and calls for Hezbollah to withdraw its fighters to a distance of about six miles (10 kilometers) from the border.[80] Negotiations are critical, but they will not be easy. Hezbollah has formally rejected negotiating a de-escalation proposal until the war in Gaza ends. 

U.S. leadership will be important. As Henry Kissinger remarked, “One has to remember that every progress that has been made towards peace in the Middle East has come under American leadership.”[81] Preventing an all-out war between Israel and Hezbollah is likely the next test.

Seth G. Jones is senior vice president, director of the International Security Program at CSIS, and author most recently of Three Dangerous Men: Russia, China, Iran, and the Rise of Irregular Warfare (W.W. Norton). Daniel Byman is a senior fellow at CSIS, professor at Georgetown University’s School of Foreign Service, and author most recently of Spreading Hate: The Global Rise of White Supremacist Terrorism (Oxford). Alexander Palmer is an associate fellow in the Transnational Threats Project at CSIS. Riley McCabe is a program manager and research associate at the Transnational Threats Project at CSIS.

The authors wish to thank Joseph S. Bermudez Jr. and Jennifer Jun for assistance with satellite imagery. Thanks also to Katherine Trauger for her invaluable research assistance.

This brief was made possible through general support to CSIS. No direct sponsorship contributed to this brief.

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