An Expert Explains: Why has Israel invaded Lebanon — and what to make of the war so far

Hours after the IDF began its offensive, Iran fired a barrage of ballistic missiles at Israel. As Israel considers its response to Iran, the Lebanon gambit is crucial for its strategic interests.

Why did Israel choose to invade Lebanon now?

For Israel, there has never been a larger geopolitical window to press against Hezbollah, the Iran-backed Shia military and political group, than now. Through Israel’s year-long war in Gaza, the United States has provided steady tailwinds in the form of sustained arms supplies, despite some political dithering. In the region, Israel’s new Arab partners have restricted themselves to rhetorical criticism and diplomatic efforts for a ceasefire. This did not change as Israel expanded its target profile across states, with the Arab nations offering no punitive threats, whether economic or political.

With Iran’s new moderate government focused on economic recovery and sanctions relief by engaging the West, Israel’s first major gambit was to kill Ismail Haniyeh, the political leader of Hamas, in the heart of Tehran. The harsh punishment that Supreme Leader Ayatollah Ali Khamenei promised in response never came, with Iran choosing “strategic patience” instead. To Israel, it confirmed that a window for escalation indeed exists, as it expanded air strikes to eliminate top leaders of the so-called “axis of resistance” — Iranian overseas proxies Hezbollah, Hamas, and the Houthis — leading to Nasrallah’s assassination. This hunt has not stopped, as the IDF’s air strikes on Beirut show.

Hezbollah has long been the biggest and most proximate manifestation of the Iranian threat, located in the north at Israel’s jugular. Israel’s long-time objective has been to push Hezbollah to the north of the Litani river in Lebanon, where the UN Security Council’s Resolution 1701 mandates it to be. Defence Minister Yoav Gallant had underlined this objective as early as on December 6, 2023 — and having destroyed Hezbollah’s senior leadership, the IDF now looks to decimate its rank and file.

Where does Hezbollah stand in the current situation?

While Israel holds the geopolitical and military advantage, Hezbollah too has evolved significantly since its last war with Israel in 2006. The group has gained crucial combat experience in Syria and Iraq over the past decade, fighting an array of rebel and jihadist forces. Fighting alongside the Russians and Syrian government forces, Hezbollah was credibly viewed as the most effective fighting force in Syria, exhibiting strong discipline and training. It has stockpiled a very large arsenal of rockets and missiles, and the IDF estimates it has 25,000 active fighters, with tens of thousands in reserve.

Hezbollah is also the only force that has effectively forced an Israeli withdrawal from any Arab territory in this century, by fighting the IDF to a stalemate in 2006, and bogging down Israeli military units in urban guerrilla warfare. That Hezbollah retains its battlefield effectiveness despite the loss of senior command was evident when the IDF lost eight soldiers on October 2, its biggest single-day setback since the two sides began exchanging fire a year ago.

What does each side — Israel and Hezbollah — aim to achieve in this war?

Each side sees ‘victory’ differently.

Israel’s casus belli is the “return of (displaced) citizens of Northern Israel to their homes”. The military necessities to service this are vague enough for Israel to withdraw whenever it determines Hezbollah to have been degraded enough in South Lebanon. However, the IDF’s widening evacuation calls signal an intent to exploit the window for escalation toward the “decisive victory” it has long sought (as David Daoud, a Senior Fellow on Israel, Hezbollah, and Lebanon at the Foundation for Defense of Democracies, noted in 2016).

For Hezbollah, the threshold for ‘victory’ is far lower — it is merely survival. As Nasrallah once asserted, “as long as there is one fighter who fires…the resistance (muqawamah) still exists”.

If Israel looks to push further north into Lebanon to exploit its window of opportunity, the likelihood of a protracted war of attrition will increase. Also, “decisively” eliminating Hezbollah is a far more difficult proposition than doing the same with Hamas in Gaza (where Israel’s military objectives are being increasingly questioned).

Hezbollah has integrated itself within Lebanese society and government, outpacing the state’s ability to deliver public goods, even though its image has been dented by economic mismanagement and the Beirut port explosion of 2020. With both the UN Interim Force in Lebanon (which includes a 900-strong Indian battalion) and the Lebanese government harshly criticising the Israeli invasion, the IDF also risks providing Hezbollah a fresh plank to consolidate domestic support. The provenance of its popularity was precisely this — to eject Israeli troops from Lebanon.

As the death toll in Lebanon balloons (it is officially 41,000-plus in Gaza), the IDF campaign faces new costs. Thus far, as Hamas sporadically retaliated in Gaza, the cost for Israel was defined in indirect, geopolitical terms — that is, the degree to which Arab states and other allies would tolerate the destruction.

In Lebanon, however, the cost is defined in direct, military terms. Perhaps most significantly, the Lebanese Army has now actively joined the war, fighting the IDF directly — the first military force-on-force engagement in the region in years.

A new phase of the war in the Middle East is playing out in Lebanon, again.

(Bashir Ali Abbas is a Research Associate at the Council for Strategic and Defense Research, New Delhi)