U.S. Vice President JD Vance dropped his plans to attend the technical talks in the Swiss mountaintop resort of Buergenstock on Thursday night.

Sources familiar with Tehran confirmed to the Reuters that Iran's lead negotiator, Mohammad Baqer Qalibaf, similarly pulled out of the scheduled Friday, June 19 meeting.

The diplomatic breakdown coincides with a severe surge of violence in Lebanon, threatening to disrupt the peace process before it begins.

Israeli airstrikes killed 18 people, according to Lebanese authorities as Reuters cited, while Iran-backed Hezbollah militants killed four Israeli soldiers.

While the interim deal requires an immediate termination of military operations on all fronts, Israel was left out of the negotiations and maintains it is not a party to the deal.

The cancelled meeting was intended to solidify a memorandum of understanding signed earlier this week by the U.S. and Iranian presidents.

The initial pact extended a ceasefire for at least 60 days to allow both sides to negotiate a lasting agreement. However, the deal delayed highly volatile issues, including Iran's nuclear program, for later discussion.

Iranian Supreme Leader Ali Khamenei has already signaled that the peace talks will not be easy.

The White House indicated that the American delegation was prepared to depart before the sudden postponement.

"But the logistics of these negotiations have never been simple or predictable," the White House spokesperson said in a statement on Thursday night. There was no immediate response from Iran's ‌government.

The Swiss Foreign Ministry confirmed the talks have been postponed but stated that Switzerland remains ready to facilitate the process as preparatory work continues.

Additional friction has emerged over the format of the talks; U.S. officials intended to hold a formal signing ceremony in Switzerland, but Iran’s foreign ministry dismissed the plan as unnecessary since both presidents had already signed the pact.

The war, which erupted on February 28 with U.S. and Israeli air attacks on Iran, has killed at least 7,000 people, mostly in Iran and Lebanon.

Despite the diplomatic bottleneck, global energy markets saw slight relief this week as oil prices dropped slightly following the resumption of commercial tanker movements through the strategic Strait of Hormuz, which was previously blockaded by Iran.