US and Iranian negotiators scrapped plans to meet in Switzerland on Friday, leading to renewed uncertainty about the timing of talks that would turn a memorandum to end three months of fighting into a more permanent peace deal. Talks could also be complicated by an escalation of fighting between Israel and Hezbollah militants based in Lebanon.

Preparations for technical talks to start in the Swiss mountaintop resort of Buergenstock were far advanced when US Vice President JD Vance said on Thursday he had dropped plans to attend. Earlier on Thursday, a sources said Iran’s lead negotiator Mohammad Baqer Qalibaf was not planning to attend.