Washington — U.N. Ambassador Mike Waltz said Sunday that the U.S. is "never going to take an approach of trust" with Iran as U.S. officials are expected to head to Islamabad for a second round of talks in the coming days.

"Any deal that comes out of this will have to absolutely be verifiable and be enforceable," Waltz said on "Face the Nation with Margaret Brennan."

President Trump said earlier Sunday that U.S. representatives would travel to Pakistan for the talks with Iran. Iranian state media reported Sunday that Iran has not decided whether it will take part in the talks with the U.S.

Asked whether the intended talks will be a presentation of terms or a prolonged negotiation, Waltz said he expects the talks will be a "continuation of the terms that the vice president offered a week ago."

The first round of negotiations last weekend, led by Vice President JD Vance, failed to yield an agreement. Vance told reporters at the conclusion of the talks that the Iranians had "chosen not to accept our terms." 

Waltz argued that the U.S. is seeing the "highest level engagement in the history of the Iranian regime, with the Vice President leading," along with "historic cease fire talks going on between the Israelis and the Lebanese." 

"The Iranian economy is devastated, and they've never been — I can tell you, here at the United Nations — they've never been more diplomatically isolated," Waltz said. "So Iran does not have the cards and we are confident they will come to the table, and finally give up their obsession with having a nuclear weapon."

Multiple sources told CBS News that Vance, along with Middle East envoy Steve Witkoff and the president's son-in-law, Jared Kushner, will be traveling to Islamabad for the talks with Iran. The trio is expected to arrive Monday evening for talks on Tuesday.

Asked about the significance of having Vance participate in the talks, Waltz said "the vice president leading shows the level of engagement from the U.S. side — that we are absolutely serious."

But Waltz acknowledged that "the Iranian side is in a bit of chaos" due to "the devastating strikes on their leadership." He said "there is no trust on this side," while pointing to "extensive discussions" with the International Atomic Energy Agency, which he said would have a "key role in ensuring Iran lives up to any deal." 

The president said on Sunday as he announced that negotiators would be returning to Islamabad that the U.S. is "offering a very fair and reasonable DEAL, and I hope they take it." He said if Iran doesn't take the deal, the U.S. "is going to knock out every single Power Plant, and every single Bridge, in Iran."

Mr. Trump has repeatedly threatened to destroy Iranian infrastructure. The threats grew increasingly more aggressive earlier this month, culminating in a threat on April 7 that a "whole civilization will die tonight" without a deal to reopen the Strait of Hormuz. Hours later, a two-week ceasefire was announced. 

"NO MORE MR. NICE GUY!" Mr. Trump wrote in a social media post on Sunday. "They'll come down fast, they'll come down easy and, if they don't take the DEAL, it will be my Honor to do what has to be done, which should have been done to Iran, by other Presidents, for the last 47 years."

On Saturday, Iran reimposed restrictions on the Strait of Hormuz after Mr. Trump said the U.S. blockade of the key waterway would remain in effect until a deal was reached on Tehran's nuclear program. A day earlier, Iran said it would reopen the strait to commercial vessels, and Mr. Trump said Iran had agreed to "never close the Strait of Hormuz again." 

Amos Hochstein, who served as a top energy and national security advisor during the Biden administration, said Sunday on "Face the Nation" that "no matter how the war ends, the Iranians now have a card they never had before," pointing to their control over the Strait of Hormuz. 

"In theory, we knew they can close the straits, but they never did," Hochstein said. "And now, for the foreseeable future, they have this card against us and against their neighbors."