The American push to quickly begin high-stakes talks with Iran hit a snag Friday, just days after the signing of an agreement that opens a two-month window for negotiations on Tehran’s nuclear program and returning oil traffic through the Strait of Hormuz to prewar levels.

Iranian officials did not travel as planned to Switzerland, insisting that Israeli strikes on Iranian-backed Hezbollah militants in Lebanon must stop before the talks can take place, according to three regional officials and a person familiar with the matter. They were not authorized to publicly discuss the ongoing mediation to try to get the talks rescheduled and spoke on condition of anonymity.

The situation was fluid as Israel and Hezbollah agreed on Friday to renew their ceasefire, according to a U.S. official and regional officials. It remains to be seen whether that could help put the U.S.-Iran talks back on track.

In Washington, President Donald Trump lashed out once again in the midst of the intensified fighting in Lebanon and the stalled nuclear talks.

“We didn’t meet out of desperation, Iran did,” Trump wrote in a social media post Friday. “They are FINISHED! We’ll play out the 60 days. They get no money, not ten cents!”