If the Iran War is resumed, how will Hezbollah react?

Lt. Col. Sarit Zehavi (IDF, Res.) is founder and president of Alma, an Israeli institute specializing in security challenges along the Lebanese border. She served for fifteen years in the IDF Intelligence Corps, initially in research and analysis and later with the Northern Command. Amid growing reports of a potential renewal of war with Iran, the central question regarding Israel's northern arena is what would happen on the Lebanese border in this scenario.

While it is impossible to predict enemy decision-making with certainty, Israel’s working assumption is that if Iran is struck, Hezbollah will intervene. Israel has already conveyed a clear warning to this effect. If Hezbollah chooses to join the fighting, Israel will strike hard, striving to reach Hezbollah areas where it has not yet operated, deepen its military achievements, and roll back the months of military rehabilitation Hezbollah has carried out, including ongoing weapons smuggling through Syria.

Crucially, an Israeli response will not be bound by the old equations that the late Hezbollah chief Hassan Nasrallah once tried to enforce. The era of symmetrical, "eye for an eye" exchanges is over. The central lesson of October 7 is that proportional containment is a deliberate trap, one that allows a terror army to build up its forces undisturbed while Israel plays a game of calculated equations. Today, Israel's operational doctrine is based on neutralizing capabilities, which is not a proportional exercise.

Because a ceasefire is currently in place and Israel is operating under specific understandings regarding Lebanon, current IDF strikes remain measured and focused primarily, though not exclusively, within the areas a few kilometers across the border where Israeli forces are deployed. Yet despite these measured strikes, Hezbollah continues to rebuild its strength with every passing day of the ceasefire. Once war is launched against us, as demonstrated this year when Hezbollah entered the last war by firing rockets at northern Israel, proportionality is off the table in favor of neutralizing the organization's capabilities to ensure the threat does not grow.

I was recently asked, "Do you feel safer?" My answer was yes. As long as the IDF remains deployed in southern Lebanon, residents of the North feel significantly safer. That deployment provides an additional defensive line inside Lebanese territory. It has ended the unacceptable pre-war reality in which Hezbollah operatives stood directly on the border fence and maintained terror infrastructure visible to mothers and children from their kitchen windows.

At the same time, because the Iranian issue remains unresolved, northern Israelis live with the constant awareness that daily life can be upended at any moment, including the closing of the skies, simultaneous fire from Iran and Hezbollah, and only seconds to reach bomb shelters. This constant tension makes maintaining a routine and planning for the future difficult for all Israelis, and it is experienced far more intensely by residents of the North.

Meanwhile, Tehran is doing everything it can to deceive the Americans and drag out negotiations indefinitely in order to buy time to advance its three core projects: its regional proxies, its missile program, and its nuclear ambitions. Some argue that time is working against the Iranian regime due to its severe economic crisis and international sanctions. However, as we have seen in North Korea, authoritarian regimes can let their citizens starve for decades and still remain in power.

Furthermore, the notion that Iran is under an airtight siege is contradicted by a recent Reuters investigation revealing that Iran's Ministry of Defense operates a secret network of over 5,000 front agencies to import at least $2 billion in military hardware, explosives, weapons components, and heavy trucks from China, Russia, Germany, and other sources to evade sanctions and rebuild its missile and drone arsenals. Just as we see that Iran is actively working to rehabilitate its military capabilities, we must assume Hezbollah is doing the exact same thing in Lebanon.