The fragile United States-Iran peace agreement is hanging by a thread as Israel intensifies its military campaign in southern Lebanon, raising fears it could unravel before formal negotiations are completed.

The agreement, which the US and Iran signed earlier this week, triggers a 60-day negotiation period for the two to reach a formal peace deal, and talks were supposed to begin in Switzerland on Friday.

However, US Vice President JD Vance cancelled his flight to Switzerland on Thursday night at the last minute after Israeli bombing in southern Lebanon, which killed at least 18 people, after which Iran said its negotiators were not prepared to begin talks until the agreement, which stipulates that Lebanon is included in the ceasefire, showed signs of being implemented.

Analysts say Israel’s continued bombardment of southern Lebanon is poised to derail any hope of ending the war in the Middle East. Israel currently occupies one-fifth of Lebanon, which it has subjected to near-daily attacks since early March. More than 3,000 people have been killed, and more than one million have been displaced from their homes.

While the US-Iran agreement stipulates that both sides will commit to ensuring the “territorial integrity and sovereignty of Lebanon”, Israeli officials have stated this week that their forces will not withdraw from the territory. Ministers in Israel have said “all of Lebanon must burn.”

So, can the deal survive in the face of Israeli bombing? And can President Donald Trump rein in Israel’s Benjamin Netanyahu?

Why have Iranian and US negotiators cancelled trips to Switzerland?

Neither side has given an official reason for cancelling trips to begin the awaited talks, which were to be held at the Burgenstock Resort in Stansstad, near Lucerne in central Switzerland.

A statement from the White House noted that “the plans for the upcoming technical talks have not been finalised,” adding that the Vance-led delegation is “prepared to depart at the first available opportunity”.

However, it added, “the logistics of these negotiations have never been simple or predictable. As of now, the Vice President is not departing tonight.”

Iran’s semi-official Tasnim news agency reported that there was no confirmation that Iranian negotiators would travel for talks, because they first wanted ⁠to see signs that the interim agreement, which includes Lebanon in the US-Iran ceasefire, is being implemented.

The Swiss Foreign Ministry followed up with a statement, saying talks to implement the preliminary deal struck between Tehran and ⁠Washington to end the war have been “postponed”.

No new date has yet been set for talks to commence, despite the 60-day clock for a deal to be reached beginning on Thursday this week.

What’s happening in Lebanon?

Just after midnight local time on Thursday night (21:00 GMT), residents in southern Lebanon woke up to the start of an intense Israeli bombardment of their villages and cities, hours before US-Iran talks were scheduled to begin in Switzerland.

The attacks have so far killed at least 18 people and wounded dozens, with the largest number of bodies pulled out from a bombed-out residential building in Harouf village.

Israel has been on one of its deadliest sprees of attacks on southern Lebanon since its ally, the US, came into an agreement with Iran to end the hostilities on all fronts – including Lebanon.

Israel began near-daily attacks on Lebanon in early March, when the Iran-backed Lebanese group Hezbollah began firing rockets into Israel in response to the US-Israeli attacks on Tehran that killed the supreme leader, Ayatollah Ali Khamenei, and other top Iranian officials.

Israeli attacks have continued despite a US-brokered “ceasefire” in April. Now, despite the US-Iran memorandum of understanding (MoU), they are continuing.

In a statement on Friday, Israel’s military said attacks on southern Lebanon overnight, which have continued through the morning, were a response to Hezbollah’s “repeated violations of the ceasefire”.

Hezbollah acknowledged attacks on Israeli military positions inside Lebanon. Soon after, the Israeli military announced that four of its soldiers had been killed during combat in Lebanon.

Netanyahu’s political ally, Itamar Ben-Gvir, the far-right Israeli national security minister, said “all of Lebanon must burn.

“With all due respect to the Americans, Israel must make it clear to the entire world that the blood of our sons and the security of our citizens are not forfeit,” Ben-Gvir wrote in a post on X, adding that, in the region, you needed to “go berserk. To obliterate. To crush the terror”.

What does the peace agreement say about Lebanon?

The first clause of the MoU signed by the US and Iran on Wednesday this week addresses the question of Lebanon.

The US and Iran have agreed to the “immediate and permanent termination of military operations on all fronts, including in Lebanon”, it states.

Additionally, it says, both sides will commit to ensuring the “territorial integrity and sovereignty of Lebanon”.

However, there is no mention of Israel in the MoU at all, leaving interpretation of this clause wide open, experts say.

Given that the agreement is solely between the US and Iran – Israel and Hezbollah are not signatories – it is unclear how a ceasefire in Lebanon would be implemented, or whether it means Iran must stop funding Hezbollah.

Iran’s Foreign Ministry spokesperson Esmaeil Baghaei has noted that Tehran “does not separate the United States and the Israeli regime”, adding that it is the responsibility of the US to ensure Israel respects commitments made under the memorandum.

How has Israel responded to the US-Iran agreement?

There is fury in Israel over the deal – and political allies and opposition alike are circling Prime Minister Netanyahu over it.

Moreover, Israel was reportedly neither privy to negotiations nor allowed to review the text before it was signed by US President Donald Trump and Iranian President Masoud Pezeshkian on Wednesday.

Netanyahu has said “the battle is not over yet,” and “Israel still faces additional challenges,” noting that the military would not withdraw from occupied Lebanese land.

Israel “will restore security to the north”, and this requires “maintaining the security strip in southern Lebanon”, from which Israel will not withdraw “as long as Israel’s security needs require it”, Netanyahu said.

On Monday, Defence Minister Israel Katz said in a statement: “Netanyahu and I are pursuing a clear policy under which the [military] will remain in the security zones in Lebanon, Syria and Gaza for an unlimited period of time in order to protect the border and Israeli communities from there against jihadist elements.”

These statements come against the backdrop of simmering tensions between Washington and Israel.

At the G7 summit in France, Trump criticised Netanyahu’s bombing tactics in Lebanon that have led to large numbers of civilian casualties.

He told reporters from the sidelines of the summit that Israel had been fighting Hezbollah “too long and too many people are being killed”.

“You don’t have to knock down an apartment house every time you’re looking for somebody because there’s a lot of people in those apartment houses – and they’re not all Hezbollah,” he said.

Vice President Vance also lashed out at Israeli cabinet ministers for speaking out against the deal on Thursday. “What is your exact proposal? You’re a country of nine million people. You can’t just kill your way out of solving every single national security problem that you have,” he said, addressing Israeli leaders.

Could Israel torpedo the peace deal?

Ali Vaez, director of the Iran Project at the International Crisis Group, told Al Jazeera that the onus is now on US President Trump to “decide whether he wants the MoU to stand or not”.

“If he wants the deal to survive, he has to exercise American leverage, not just to reprimand Netanyahu, but to force him to stop the war in Lebanon,” he said.

From Tehran’s perspective, Vaez said, “if [Trump] is unwilling or unable to rein Netanyahu in, no deal with the US is worth the paper it is written on.”

Tahani Mustafa, a visiting fellow on the Middle East and North Africa programme at the European Council on Foreign Relations, said “the MoU does not necessarily guarantee that Israel is going to behave or not try to torpedo the process, especially given the tensions between the US and Israel,” in addition to domestic pressure on Netanyahu, who faces national elections by October this year.

“It [Israel] could well try to torpedo this [deal], and we’ve seen in the past where Israel has been defiant despite what the US has often tried to sort of push it towards,” she told Al Jazeera.

The only thing that can guarantee further negotiations to secure the deal “is serious, hard pressure on Israel – but Washington has shown that it really doesn’t have the political will to do that”, she added.

That leaves keeping the peace talks on track down to Iran, “even if that means Israel’s bombing of Lebanon continues, which it most likely will”, Mustafa noted.

Vaez of Crisis Group, however, said continued killings in Lebanon would quickly unravel the negotiations.

“Iran might be able to afford to delink Lebanon at some point down the road, but not when the ink isn’t fully dry on the MoU,” he concluded.