United States Vice President JD Vance has arrived in Switzerland for talks with Iranian officials on implementing the interim deal to end the US war with Iran.

The US and Iran earlier this week agreed to a 60-day ceasefire extension for the negotiations, but Iran’s Islamic Revolutionary Guard Corps (IRGC) on Saturday announced the closure of the ⁠Strait of Hormuz in response to Israeli attacks in Lebanon – although the US military said commercial vessels kept operating.

The talks, with the presence of the mediators, were expected to start in the Swiss mountain resort of Buergenstock “during the course of the morning”, Switzerland’s Federal Department of Foreign Affairs said in a statement on Sunday.

The delegations are set to be led by Vance and Iranian chief negotiator Mohammad Bagher Ghalibaf.

“I think we’re going to hopefully make progress on the nuclear issue, make progress on the Lebanon ceasefire issue,” with a “couple days of talks” likely, Vance told reporters at Joint Base Andrews in Maryland before departing for Switzerland.

An Iranian delegation arrived in Switzerland late Saturday, state media and the Swiss Foreign Ministry said, with Iran’s official broadcaster reporting it included Parliament Speaker Ghalibaf and Foreign Minister Abbas Araghchi.

Mediator Pakistan said its Prime Minister Shehbaz Sharif and the army chief, Asim Munir, had also arrived in Switzerland to participate in the talks.

Al Jazeera’s Osama Bin Javaid, reporting from Buergenstock, Switzerland, said the sides would try to bridge the gap between their positions during the talks.

“And that is why you’re seeing the highest level of participation,” he said.

“The US immediately wants to go into the nuclear issue. The Iranians want an end to the fighting in Lebanon,” our correspondent said.

A halt to fighting in Lebanon was one of the conditions agreed this week in the interim deal to extend the US-Iran ceasefire for 60 days and start talks on Tehran’s nuclear programme and other issues.

But the deal is already coming under strain, as Israel continued attacks in Lebanon on Saturday, killing dozens of people, with Iran’s IRGC citing the strikes as it declared the Strait of Hormuz shut. The US military said commercial vessels had continued operating in the waterway.

Pointing to what it called Israeli “crimes” in Lebanon that violated US commitments to a ceasefire, the IRGC warned ships would be at risk if they approached the strait, a vital conduit for global oil and gas supplies.

But US Central Command (CENTCOM) said 55 merchant ships transited the strait on Saturday, with more than 17 million barrels of oil bound for global markets. US forces will ensure commercial traffic continues, CENTCOM said.

Trump said no toll would be charged for passage through the strait during or after the 60-day ceasefire – unless the US imposes one should peace talks fail.

In a social media post, he cited the possibility of a toll levied by the US “for services rendered as the Guardian Angel to the countries of the Middle East” if a deal to end the war is not completed.

Wolfgang Pusztai, a security analyst and former defence attache for the Austrian government, said Iran should be cautious over its renewed threat to close the Strait of Hormuz, as the vital waterway serves Tehran’s allies more than its enemies.

“The Strait of Hormuz foremost is certainly a very important tool in the strategy of Iran. There is absolutely no doubt about it. But Iran needs to be careful not to overplay this card,” said Pusztai.

“One needs to remember that most of the ships passing through the Strait of Hormuz are not heading to the United States or to Europe. They’re heading to India, China and Pakistan.”

Iran seeks implementation of the deal

The developments could complicate talks to advance the interim deal brokered by Pakistan and signed on Wednesday by presidents Donald Trump and Masoud Pezeshkian to end the almost four-month war.

Mohammad Mokhber, an adviser to Iran’s supreme leader, Ayatollah Mojtaba Khamenei, accused the US on X of failing to implement the first clause of its 14-point interim deal with Iran, which stipulates a ceasefire “on all fronts”, including Lebanon.

He said that if the deal were not implemented, the flow of energy through the region would remain halted.

Al Jazeera’s Resul Serdar Atas, reporting from Tehran, said the Iranian delegation in Switzerland was likely to focus on Articles 1, 4, 5, 10 and 11 of the memorandum of understanding (MoU).

“These include the cessation of hostilities in Lebanon, the lifting of the US maritime blockade, the reopening of the Strait of Hormuz, the release of Iranian frozen assets and, of course, the lifting of US sanctions when it comes to Iran’s oil sector and petrochemical products and related sectors,” our correspondent said.

“So the Iranians are not looking for these files to be concluded in one meeting here, but at least they want the initiation of the implementation,” he added.

“Why does Lebanon matter so much for Iran? Overall, it’s about Iran’s geopolitical standpoint. So if Iran wants to remain as a regional power, Tehran has to keep the “axis of resistance” alive. Iran has invested in Hezbollah through the decades. So it is about Iran’s regional influence. It is also sending out a message to its allies and proxies in the region that Tehran is not going to leave them alone.”

The Lebanon truce appeared fragile as Israeli forces continued their attacks on the country on Saturday, killing dozens of people, according to Lebanese state media.

The Iran-aligned Hezbollah group also announced attacks on Israeli forces.

Israel claimed it was responding to attacks from Hezbollah, while the Iran-backed fighters said Israel had repeatedly violated the truce since Friday, and it would not allow Israel “freedom of movement” in Lebanon.

The Israeli military said one soldier was killed in combat, the fifth such death since the US-Iran deal was reached.

Israeli broadcaster Channel 12 reported late on Saturday that the prime minister and defence minister had ordered the military to hold fire in Lebanon, but that the military would not withdraw from captured territory.