U.S. Ambassador to the United Nations Mike Waltz said the Trump administration is "laser focused" on addressing Iran's nuclear program in an interview Sunday on "Face the Nation with Margaret Brennan," as the U.S. and Iran hold thorny talks in Switzerland.

Earlier Sunday, Vice President JD Vance and other U.S. officials entered a conference room with Iranian Foreign Minister Abbas Araghchi and Parliament Speaker Mohammad Bagher Ghalibaf, a rare direct meeting between high-level envoys from both countries. Ghalibaf, in particular, is described in some quarters as a hardliner: He helped oversee the creation of Iran's missile program and allegedly bragged about cracking down on protesters.

"None of these senior members of this genocidal regime are good guys by any means," Waltz said. "They certainly wouldn't pass an FBI background check. No one expects that. But, at the end of the day, the administration, our administration, is taking a pragmatic approach."

Waltz said Sunday the administration's focus is on preventing Iran from obtaining a nuclear weapon, in contrast with what he called a "policy drift" in prior U.S. goals with Iran. But he added that "we know the type of people that we're dealing with," citing Iran's deadly crackdown on demonstrations earlier this year and its history of imprisoning American citizens.

In the past, the Trump administration has laid out a more sweeping set of war aims, with President Trump vowing to destroy Iran's missile program and set the stage for Iranians to overthrow the regime. More recently, however, Mr. Trump has focused specifically on nuclear issues, saying it's "OK" for Iran to have ballistic missiles and he isn't vying for "regime change."

On the U.S. side, Waltz confirmed that "technical experts" from the Department of Energy are involved in the negotiations, and will help address the "nitty gritty details" of the fate of Iran's nuclear program, including its stockpile of highly enriched uranium.

The exact structure of a potential U.S.-Iran nuclear deal remains unclear. The two sides signed a memorandum of understanding last week that said they "agreed to resolve the disposition of stockpiled enriched material," with downblending the material cited as the "minimum" outcome. But the document included few specifics, leaving a mountain of issues that will need to be addressed in technical talks over the next 60 days.

Mr. Trump has long said he does not want Iran to enrich uranium — a red line that Iran has frequently rejected. Iran insists its nuclear program is intended for peaceful purposes, and U.S. intelligence agencies found last year that Iran wasn't actively developing weapons, though it has enriched uranium beyond the level required for most non-military uses.

Waltz told CBS News on Sunday the goal is "Iran not having a nuclear program," appearing to stick with Mr. Trump's red line. He said the Trump administration wants the program "permanently destroyed, as opposed to the past, where it was ongoing, and we were basically bribing them to not continue."

Any deal between the U.S. and Iran, Waltz said, would be "all about verification," with "no trust" in Iran needed. And in exchange for complying with a deal, Iran could receive "carrots" in the form of sanctions relief.

Some congressional Republicans have criticized the idea of lifting sanctions, warning it could free up cash for Iran to fund its conventional military or financially support regional proxies like Hezbollah. Waltz said Sunday any money that Iran is allowed to collect from oil sales will be "going to places that we can still monitor," and isn't going into a "slush fund."