What is Israel’s war in Lebanon and why could it shatter the Iran ceasefire?

By Nadeen Ebrahim, Sarah Tamimi, CNN

(CNN) — On the first day of the US-Iran ceasefire on Wednesday, Israel conducted its biggest wave of strikes on Lebanon since the war began, killing at least 182 people, a move that threatens to derail an already fragile truce.

Iran said the ceasefire included Lebanon, a position echoed by Pakistan, which helped mediate the deal. Both Israel and the United States said it did not.

US and Iranian delegations are set to begin negotiations in Islamabad this weekend, with the question of whether Lebanon is covered by the ceasefire emerging as a potential wildcard.

“The Lebanese front may ultimately undermine efforts to sustain the ceasefire,” said Danny Citrinowicz, senior researcher in the Iran and the Shi’ite Axis Program at the Institute for National Security Studies (INSSS) in Tel Aviv. From Tehran’s perspective, Israel’s continued attacks on Lebanon “may justify a renewed response against Israel,” he added.

Here’s what to know.

Why is Israel striking Lebanon?

Hezbollah, an Iran-backed Shiite Islamist movement with one of the most powerful paramilitary forces in the Middle East, has engaged in decades of conflict with Israel from its base in neighboring Lebanon.

Israel launched a full-scale war on Hezbollah after the group fired at Israeli-held territory in support of Hamas following that group’s October 7, 2023 attack on Israel.

In November 2024, Israel approved a ceasefire deal that required it to withdraw from Lebanon. But the Israeli forces continued to hold positions beyond the deadline and carried out near daily strikes, citing Hezbollah violations.

After Israel killed Iran’s Supreme Leader Ali Khamenei in an airstrike in late February, Hezbollah began firing at Israel.

The Israeli military retaliated by launching an intense wave of airstrikes on what it said were Hezbollah positions and sent troops deeper into Lebanese territory, seeking to establish a buffer zone in the south of the country.

More than 1 million people have been displaced in Lebanon since the start of the latest conflict. As of Tuesday, at least 1,530 people had been killed and 4,812 wounded, according to the health ministry.

Defense Minister Israel Katz has said the Israeli military intends to destroy villages in southern Lebanon and has barred the 600,000 Lebanese who fled from returning to their homes “until the safety and security of northern Israeli residents is ensured.”

The destruction will be “in accordance with the Rafah and Khan Younis model in Gaza,” Katz said, referring to two Palestinian cities that Israel bombed heavily during the war in Gaza.

Far-right Finance Minister Bezalel Smotrich last month suggested annexing southern Lebanon.

“The current campaign in Lebanon must end with a fundamental change: the Litani must become our new border with the State of Lebanon,” he said, referencing the river that separates southern Lebanon from the rest of the country.

Human rights experts have warned that open-ended mass evacuation orders and the new security borders mandated by Israel amount to a “possible war crime.”

Is Lebanon part of the ceasefire deal with Iran?

Over the past 48 hours, officials involved in negotiations gave conflicting statements about whether Lebanon is included in the ceasefire.

Unlike most ceasefire agreements, there are no publicly available documents underpinning this one. Much of what is known about the deal came from social media posts by Trump, Pakistani Prime Minister Shehbaz Sharif and Iranian Foreign Minister Abbas Araghchi.

Sharif said in an X post on Wednesday that Iran and the US agreed to “an immediate ceasefire everywhere including Lebanon.”

Israel later contradicted Sharif’s comments.

“The battle in Lebanon continues and the ceasefire does not include Lebanon,” Israel’s military spokesperson Avichay Adraee said Wednesday on X as he issued evacuation orders for swaths of southern Lebanon. Israeli Prime Minister Benjamin Netanyahu’s office echoed that statement.

Both US President Donald Trump and Vice President JD Vance have also denied that Lebanon was part of the ceasefire agreement in the war with Iran.

Lebanon on Wednesday experienced the heaviest round of attacks across the country since the war began.

Large explosions were heard and smoke seen Wednesday morning at the Israel-Lebanon border, with residents telling CNN there was no safe place to go.

According to the Israeli military, more than 100 Hezbollah command centers and military sites were struck simultaneously across the country. Lebanon’s health ministry said at least 182 people were killed and 890 were wounded in the attacks.

Why could Israel’s strikes on Lebanon derail the ceasefire deal?

Following Netanyahu’s claim that the ceasefire didn’t include Lebanon, Araghchi demanded an end to “massacres in Lebanon” and other Iranian officials warned that the attacks constitute a violation of the truce.

“The Iran–US ceasefire terms are clear and explicit: the US must choose – ceasefire or continued war via Israel. It cannot have both,” he wrote on X. “The ball is in the US court, and the world is watching whether it will act on its commitments.”

On Wednesday, Iran’s Revolutionary Guard Corps warned the US and Israel it would deliver what it called a “regret-inducing response” if attacks on Lebanon continued.

The IRGC claimed that shipping through the Strait of Hormuz slowed sharply and then stopped as a result of Israel’s attacks.

Experts say only intervention by Trump can restrain Israel.

Citrinowicz said Netanyahu’s commitments to keep residents of northern Israel safe and broader political considerations could make a ceasefire in Lebanon unlikely.

“This reality complicates any attempt to extend de-escalation to the Lebanese front,” he said. “President Trump will likely need to engage directly and make a strategic decision.”

Israel’s continued attacks could draw it into another war with Iran, and possibly bring in Yemen’s Iran-backed Houthi rebels, dampening any attempts of de-escalation, experts said.

Israel may be trying to “torpedo” the US-Iran ceasefire, Fawaz Gerges, professor of International Relations at the London School of Economics said, as Netanyahu tries to “salvage whatever remains of his political career in Israel.”

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CNN’s Tal Shalev, Charbel Mallo and Eugenia Yosef contributed reporting.