Vice President JD Vance said Monday that Iran had agreed to invite United Nations nuclear inspectors back into the country, declaring the first round of U.S.-Iran talks “a successful foundation” for a lasting peace agreement.

Speaking at a news conference in Switzerland after the talks, Vance sought to cast the discussions in a positive light, even as many challenges and thorny issues remain.

The return of inspectors from the U.N. nuclear watchdog, International Atomic Energy Agency, to Iran would be a “major milestone for the American people, and the first step in permanently denuclearizing or permanently ending a nuclear weapons program in Iran,” Vance told reporters. There was no immediate response from the IAEA or Iran.

Inspections were a key part of the nuclear accord that the Obama administration and five of the world’s most powerful countries signed with Iran in 2015. After President Donald Trump withdrew the United States from that accord in 2018, Iran began limiting inspections of its nuclear facilities, and it all but ended them last year after some of the sites were hit by U.S. and Israeli attacks.

Iran has repeatedly insisted that its nuclear program is for civilian purposes.

Vance also said the talks had created a process to de-escalate tensions in the Strait of Hormuz and in Lebanon, where Israel and Hezbollah, the Iran-backed militia, appear to have eased their attacks. The two issues have complicated the delicate ceasefire between the United States and Iran that was signed last week.

Qatari and Pakistani mediators said earlier that the first round of U.S.-Iran negotiations had ended with “encouraging progress,” but some analysts cautioned against being overly optimistic.

U.S. and Iranian negotiators have agreed to a “road map” for reaching a final deal within 60 days.

In other developments:

Frozen assets: Vance outlined a proposal for potentially unfreezing Iranian assets at a later date, a core demand of Iran in the negotiations. Iran’s central bank governor said earlier that “necessary memoranda were signed” to initiate the release of assets, according to an interview published by Tasnim, a semiofficial Iranian news agency, but Vance suggested there was no final agreement on the complex issue.