Vice President JD Vance declared in Switzerland that the U.S. “laid a successful foundation” in the initial phase of its ongoing peace talks with Iran, even as President Donald Trump threatened to renew attacks and a skeptical Congress questioned whether the agreement being negotiated is worth pursuing at all.

Vance, who is leading the U.S. negotiations with Iran, said on Monday that the Strait of Hormuz is currently open and that Iran has agreed to allow international inspection of its nuclear program, a safeguard that was part of the deal former President Barack Obama secured with Iran in 2015 and Trump withdrew the U.S. from in 2018 during his first term. 

The progress to allow international inspections on Iran’s enriched uranium was built at a particularly fragile moment in the 60-day ceasefire the memorandum of understanding signed by the U.S. and Iran last week established for the two countries to finalize a longer-term deal on Iran’s nuclear program and other outstanding issues. Over the weekend, Israel launched a deadly strike in Lebanon which killed at least 16 people, according to local authorities, prompting Iran to close the Strait of Hormuz over what it deemed a violation of the agreement. In response, Trump called on Iran to stop its proxies in Lebanon from “causing trouble,” threatening that if it did not the U.S. would “hit Iran very hard.” He also said during an interview with Fox News that he told Iranian delegates that if the country chose to close the Strait, they wouldn’t “make it back” to their country.

During the press conference, Vance defended Trump’s comments, accusing Iranians of engaging in “trash talk,” and said that negotiations between the two countries are still ongoing. He added that Iran and Israel have set up a “deconfliction mechanism,” but also that that a lot more needs to be done to ensure that Lebanon’s territorial integrity and Israel’s security can both be protected. 

“When things happen, the sides are actually talking to one another,” Vance said, referring to any potential conflicts between Israel and Lebanon. He added that American and Iranian “technical teams” will continue negotiations “over the weeks and days to come” following the high-level talks in Switzerland.

Many questions remain unanswered about what might be included in a potential long-term deal to end the Iran war following Vance’s press conference. The memorandum of understanding signed by Trump and Iranian leaders last week, provided a framework for negotiating a final peace deal that includes the U.S.would unfreezing Iranian assets, lifting sanctions on Iranian crude oil exports, and setting up a $300 billion fund for Iran to rebuild its economy with help from regional partners in exchange for Iran’s promise to keep the Strait of Hormuz open and not to produce any nuclear weapon.

But it is not yet clear whether Israeli forces’ withdrawal from southern Lebanon is a part of the condition for reaching a final peace deal, who would pay for the $300 billion rehabilitation fund, or how the U.S. would ensure the fund, along with Iranian assets it previously froze, would not be used to fund terrorist activities—issues that critics within Iran and the U.S. have raised concerns over. 

Vance struck an optimistic tone about the state of negotiations despite the apparently unresolved questions, however.

“We set the foundation. We haven't built the house, but we've laid a successful foundation to get to a good place for the American people,” Vance said.

An unhappy Congress could scuttle Trump’s deal

As the first round of U.S.-Iran talks conclude in Switzerland, the Trump Administration’s effort to negotiate a peace agreement is facing possible roadblocks at home. A skeptical Congress has repeatedly expressed concerns about the framework since its announcement. Sen. Ted Cruz of Texas, a Trump ally, on Friday joined a growing chorus of Republicans who have vocally criticized the President’s potential deal with Iran, saying on his podcast that the memorandum of understanding “doesn’t make any sense.” 

“The idea that we would have effectively a Marshall Plan for Iran is not remotely in America’s interests,” Cruz said, while adding that he believed Trump “was getting very poor advice on this deal.”

“Giving people who want to kill you billions and billions of dollars, from any source, historically has proven an enormous mistake,” Cruz added. 

Rep. Don Bacon of Nebraska, a moderate Republican, also opposed the deal in a social media post, saying “giving Iran leverage is a mistake.”

The dissent from congressional Republicans can’t simply be brushed off by the White House, since Congress established its authority in approving any future Iran nuclear deal in a 2015 law. Under that measure, the president must submit the text of any nuclear-related agreement to Congress within five days of it being finalized, and Congress has 30 days to vote on a resolution of disapproval, which would require a simple majority in both chambers to pass. If Congress passes such a resolution—and overcomes a potential veto from the President, a move that would require a more significant two-thirds majority—the Trump Administration would be prohibited from lifting sanctions on Iran or providing the country any economic relief, essentially nullifying the memo. 

Sen. Lindsey Graham of South Carolina, another close Trump ally, has also expressed pessimism on the Iran deal. During an interview with CBS News on Sunday, he said he expected that the diplomatic effort between the U.S. and Iran is “going to fail,” and that the U.S. will eventually take control of the Strait of Hormuz by force and start charging tolls. 

“If Iran contests control of the Strait of Hormuz by the United States, we will obliterate them,” Graham said.