When Hezbollah deputy chief Naim Qassem announced on the 13 October 23 that “Hezbollah knows its duties perfectly well, we are prepared and ready, fully ready”1, many onlooking analysts and regional decision makers would have felt with growing certainty that the Lebanese militant groups entry into the current conflict is matter of when, not if.

Since the onset of current hostilities, ignited by the Hamas incursion into southern Israel on the 7 October 23, Hezbollah’s involvement has thus far been militarily limited. Activity along Israel’s rugged northern border in the past week has involved intermittent mortar and rocket fire (see below tweet), with reports of small-scale incursions by both Hezbollah militants and members of the Palestinian Islamic Jihad (PIJ) group. Despite the Iranian-backed group already announcing fatalities from the current flare-up2, these calculated skirmishes have given the group valuable time to ascertain both the domestic and regional appetite for its wider involvement in the conflict. Hezbollah has effectively bided its time, building consensus with its sponsors in Tehran, instead of rushing into full-blown hostilities. On 16 October 23, Iranian Foreign Minister, Hossein Amir-Abdollahian threatened that any US involvement would lead to the widening of the conflict and US casualties, thus further highlighting Iran’s intention to shore up Hezbollah’s involvement in the conflict. Concurrently it has likely used the previous days to tactically probe the strength and readiness of Israeli Defence Forces (IDF) troops situated along the border whilst simultaneously portraying a united front with Hamas. High-ranking strategic planners within the IDF will have long planned for a war on multiple fronts, yet despite the impending resource-heavy ground invasion of Gaza, it is telling that a large proportion of the roughly 300,000 mobilised reservists have not been sent to Gaza but to the Northern border both to dissuade Hezbollah from becoming further involved, and as a contingency in case they do decide to increase the scale of their kinetic activity to include cross-border ground operations.

Video footage reportedly from Hezbollah showing a mortar attack against a target in the Golan Heights. Source: @PopularFront_

Given the current hesitancy for both sides to be drawn into a major conflict, what are the triggers that could cause Hezbollah to open a new front in the ongoing conflict?

Hezbollah is likely to act if the scenario presents itself where it feels the long-term strategic gains outweigh the potential risks. Despite the group’s militant roots, it is imperative to understand that any actions it takes will have far-reaching repercussions for its political branch and more broadly the civilian population of Lebanon. In the coming days Hezbollah leadership will have to make the political calculation as to whether escalation will irreversibly weaken and delegitimize the strengthened domestic position it has painstakingly built since 2006. If Hezbollah leader Hassan Nasrallah believes events will unwind in a manner that favours the group, he could sanction an escalation in hostilities.

The most likely course of action in the short term includes an Israeli ground invasion of the Gaza Strip. Given the complexity of conducting urban and potentially subterranean combat operations, the IDF will be forced to commit a large portion of its forces to Gaza. With Israel bogged down in Gaza and the capability for Iran to launch a multi-front offensive through proxies positioned in Syria, it is conceivable that Hezbollah may launch an attack against a stretched Israeli security apparatus. Moreover, the sheer destruction and inevitable loss of civilian life from a Gaza invasion may compel Hezbollah to act.

Another scenario that would cause wider confrontation is if Hezbollah believed Israel was going to conduct a pre-emptive strike targeting its stockpiles of Iranian-manufactured missiles. Israel has already set the precedent for taking such actions with the bombing of Damascus and Aleppo airfields on 13 October3 which rendered the runways at both airports unusable.

Regardless of the actions Israel takes or the strategy Hezbollah wishes to employ, its involvement will ultimately be dictated by its ideological patron Iran. Hezbollah is by far the most adept and operationally effective tool available to Iran in its array of proxies that span the Shia crescent. Iran will be acutely aware of losing such an astute regional lever especially when it has likely already achieved many of its intended outcomes, such as de-railing the Saudi-Israeli normalisation process, through its support of Hamas and PIJ.

What would Hezbollah’s involvement look like?

Hezbollah’s offensive and defensive operations are significantly defined by the hilly terrain that characterises southern Lebanon. The group have long used fortified underground positions to offset the lack of air defence and heavy mechanized forces. Large tunnel complexes up to 40m below ground were used heavily during the 2006 war and have likely been strengthened and expanded in the past seventeen years. Defensively, these underground networks give Hezbollah resilience against even the largest bunker-busting munitions available to the Israeli Air Force (IAF) enabling them to protect their supply of missiles and anti-tank munitions. Much like the unfolding situation in Gaza, to neutralise the threat of Hezbollah in Lebanon the IDF would have to commit ground forces to destroy these hardened defensive positions.

Coincidentally these underground structures and tunnels offer Hezbollah significant offensive capability. Historically the group has tunnelled across the border into Israel with the most recent large incursion culminating in 2018, Operation Northern Shield saw the IDF destroy cross-border attack tunnels. Despite the IDF stating that all tunnels have been destroyed, it is a realistic possibility that undetected tunnels still exist, or replacements have been dug, giving Hezbollah clandestine means to enter Israel and infiltrate enemy positions. The ability to conduct isolated cross-border incursions resonates heavily with Hezbollah’s military doctrine of decentralisation with five to ten-man detachments working independently. Moreover, the use of the hardened tunnels gives Hezbollah the capability to fire rockets and mortars from concealed positions using shoot-and-scoot tactics, quickly withdrawing into the hillside before Israeli counter-battery fire can target them.

The most defining element of large-scale Hezbollah offensive operations is likely to be its extensive use of missiles and rockets. Although these weapons have long acted as a deterrent the group has steadily been growing its stockpiles since 2006. Although the exact number is unknown it is estimated that Hezbollah has at its disposal at least 130,0004 rockets and missiles. The roughly 4,500 rockets that Hamas has fired since the morning of the 7 October 23 pales in comparison to the number of Hezbollah’s. The majority of this arsenal are unguided rockets including the Katyusha, Fajr-1 and Khaibar families of weapons. In isolation these land attack weapons do not pose a significant threat to Israeli air defence systems. However, it is the ability to simultaneously fire large salvos of these weapons that could potentially saturate Israeli air defence systems, with each Iron dome battery consisting of up to four launchers containing 20 Tamir missiles. Notably, it was these Tamir missiles that were urgently requested from the USA in military aid, likely due to the rapid rate of consumption of a finite supply in the first few days of the war5. Moreover, if Hezbollah were to coordinate indirect fires with Hamas, this could exacerbate the danger even further with the Iron Dome’s successful interception rate likely to fall significantly. Since its deployment in 2011, the Iron Dome system has allowed the Israeli population to live relatively unscathed and detached from the majority of the violence occurring in the West Bank and Gaza Strip. The psychological impact on Israeli civilians if urban areas such as Tel Aviv and Haifa were to come under sustained fire should not be underestimated.

It is also believed that Hezbollah has acquired precision-guided missiles (PGMs), most notably multiple variants of Scud missiles and the Iranian-made Fateh-110. These missiles have a range of up to 300km and 550km respectively, placing the whole of Israel within range from firing positions in southern Lebanon. Despite Israel’s efforts, the Islamic Revolutionary Guard Corps (IRGC) through its Quds force has used its regional partnerships with Shia militias in Iraq and the Assad regime in Syria to build a corridor through to Southern Lebanon. Iran has facilitated the smuggling of these weapons by both air and land in preparation for exactly the scenario that is playing out now. Conclusively it is highly likely that any offensive operation or escalation in hostilities would see Hezbollah use these vast stockpiles of weapons which would dictate the manner in which Israel conducted operations.

The Russia/Ukraine war has proven a stark reminder to the West that cheap Iranian drones can, albeit limitedly, defeat complex air defence systems when launched en-masse. So far, it is not believed that Iran has provided Hezbollah with the infamous Shahed 136 one-way attack UAVs, yet drone warfare is expected to play a crucial role in any Hezbollah assaults. The group has demonstrated its ability to conduct drone ‘reconnaissance’ missions against Israeli assets in the Karish gas field6 and in recent training exercises paraded heavy lift octocopters and the Iranian Rased-17. Hezbollah has the ability and know-how to operate small drones sporting improvised air-delivered munitions (IADM) to strike fixed observation and sentry posts along the Israeli border in a similar fashion to Hamas in the early hours of the 7 October 23. Where it differs is its ability to also operate larger drones with warheads in a deep strike role, something the Iran-backed Houthis had success with when they launched drones at the Saudi oil facilities in Khurais and Abqaiq in September 2019, causing “the single largest daily oil supply disruption in history”8.

However, there is also the possibility that Hezbollah’s involvement may not involve military action at all. Their involvement could simply be to keep Israel distracted with the threat of a northern front opening up. Historically Hezbollah has targeted Israeli IDF members with successful counterintelligence operations. In 2006, it compromised IDF Lieutenant Colonel Omar al-Heib who traded surveillance data in exchange for narcotics. Given the large number of IDF troops on the border with Lebanon there is a realistic possibility that Hezbollah will target IDF soldiers, especially those who are reservists for information in exchange for narcotics or payment.

Both Hamas and Hezbollah have historically lacked any armoured vehicles, creating an imbalance against the heavily mechanized IDF which has over 350 of its latest Merkava IV main battle tanks alone. Although Hezbollah has acquired some conventional mobile artillery and autocannons its most common vehicles are still modified technical and truck-based multiple-barrel rocket launchers (MBRLs). This inability to directly confront IDF mechanised brigades has taught Hezbollah to evolve its tactics and weapons. For example, Hezbollah’s elite Radwan unit employ small, highly mobile units on motorcycles, quad bikes, and light all-terrain vehicles equipped with Anti-Tank Guided Missiles (ATGMs). Even in the brief skirmishes that have occurred in the past week, Hezbollah units have successfully destroyed IDF M113 Armoured Personnel Carriers (APCs) using Russian-made Kornet ATGMs. Effective weaponry and light mobile units may have fared well for Hezbollah to date but the overwhelming firepower and numbers of the IDF will inevitably dictate how the Shia-militia conducts a full-scale assault.

Video reportedly showing a Hezbollah Anti-Tank Guided Missile (ATGM) strike against an IDF APC. Source: @War_Noir

A contrasting and more complex threat to Hamas

Despite both being supplied and trained by Iran, as already discussed Hezbollah is significantly more dynamic, powerful, and capable adversary than Hamas. So what factors and capabilities differentiate it as possibly the most powerful non-state actor? Primarily it is the ability to field a large number of troops, with an estimated standing force of 20,000, and the capacity to surge the same number of reserves during periods of conflict. Although the group’s military doctrine is enshrined in a decentralised small-unit framework, its involvement in the Syrian war taught it how to also operate as a larger more conventional army that can integrate armoured units. Furthermore, through the Syria conflict, the group has gained battle-hardened and experienced troops that have subsequently been tasked by Iran to train other proxies such as the Houthis because of their expertise.

It is not just the known capabilities of Hezbollah that pose a threat in future conflict but the unknown ones too. Israeli intelligence has long tried to identify and stymie the transfer of new capabilities from Iran to southern Lebanon, particularly that of air defence systems. Though there are unverified reports of Hezbollah acquiring platforms capable of firing surface-to-air missiles this would likely only become apparent at the onset of war. Although any air defence systems the group does have are likely to be minimal, they could impact how the IAF would conduct an ariel campaign against Hezbollah. It is the capabilities one would associate with a conventional army that exacerbate Hezbollah’s threat and cause concern for Israel’s strategic command.

Finally whereas Gaza is under a heavy blockade with Israel dictating the siege, this would not be the case with any conflict with Hezbollah. It is unlikely that Israel would be able to tangibly prevent the resupply or reinforcement of Hezbollah unless it occupied southern Lebanon, which is improbable given the current circumstances.

What Next?

A ground invasion of Gaza at this point seems inevitable, what is unknown is whether this will usher in a second stage of the conflict which embroils the wider region. Hezbollah’s entry into the conflict would directly impact the course of actions taken by Netanyahu’s unity government. It is the much greater force of Hezbollah, in conjunction with other Iranian proxy forces, which should be perceived as the greatest threat to the safety of Israel. Hezbollah should be viewed as a real danger that for all its bombastic rhetoric has the motive, capability, and willingness to open a second front at any moment, the fallout of which is likely to reverberate across the Levant.

Hezbollah’s involvement in attributable kinetic activity beyond the already existing rocket attacks on Israel will highly likely see the US enter the combat arena. This will likely be in the shape of air support from the two carrier strike groups that have been deployed to the Eastern Mediterranean. Should the US become involved in this conflict it is highly likely that Iran will no longer simply use Hezbollah as a “proxy” force but will overtly enter the conflict given the comments made by its Foreign Minister.

1 https://www.reuters.com/world/middle-east/hezbollah-says-when-time-comes-any-action-we-will-carry-it-out-2023-10-13/

2 https://www.reuters.com/world/middle-east/israeli-military-says-its-troops-killed-gunmen-who-infiltrated-lebanon-2023-10-09/

3 https://www.bbc.com/news/world-middle-east-67093081

4 https://www.csis.org/analysis/hezbollahs-missiles-and-rockets

5 https://www.bloomberg.com/news/articles/2023-10-12/pentagon-owned-stocks-in-israel-transfered-to-defense-forces

6 https://www.reuters.com/world/middle-east/israel-shoots-down-unarmed-hezbollah-drones-heading-gas-rig-security-source-2022-07-02/

7 https://www.middleeasteye.net/news/lebanon-inside-hezbollah-arsenal

8 https://www.csis.org/analysis/attack-saudi-oil-infrastructure-we-may-have-dodged-bullet-least-now