US Special Envoy Steve Witkoff, who is negotiating with Iran on a new nuclear deal, said that Tehran must "halt and eliminate its nuclear enrichment program" to reach an agreement with Washington, in what appears to be an elevation of US demands ahead of another round of talks with Iranian officials.

Witkoff's remarks on Tuesday appeared to contradict his suggestion just a day earlier that the United States would be satisfied with Iran enriching uranium to a low level for energy production.

Witkoff had stated that the Trump administration was prepared to allow Iran to enrich uranium to a low level if it was subject to strict verification, a significant shift from the White House's initial demand to dismantle Tehran's nuclear program.

According to experts, this position, if adopted during the talks, which will resume on Saturday following an initial meeting held last weekend, will give Iran a foothold in its nuclear program and put the United States at odds with Israel's goals on the issue.

"They don't need to enrich beyond 3.67%," Witkoff said on Fox News on Monday night. "It will largely be about verifying the enrichment program and then ultimately verifying the weaponization potential."

The United States is seeking to impose strict restrictions on Iran's nuclear activities and missile program, while Tehran hopes to ease the economic sanctions that have damaged its economy. Before the Trump administration's first round of talks with Iran, held last weekend in Oman, Witkoff told the Wall Street Journal that the initial US position was that Iran's nuclear program must be dismantled. However, he also indicated that the White House would be willing to make concessions to reach an agreement.

President Trump warned that he might launch airstrikes if a nuclear agreement is not reached.

Iran has long refused to negotiate a waiver of its uranium enrichment capacity as part of what it describes as a civilian nuclear program used for electricity generation and medical research.

It's worth noting that the Obama administration's acceptance of Iranian enrichment was a key factor in paving the way for the 2015 nuclear agreement with Iran. This agreement set a ceiling on uranium enrichment at 3.67%, but ultimately allowed Iran to reach enrichment levels well beyond that. This prompted Trump to describe the agreement as weak and withdraw from it during his first term.

The 3.67% enrichment level is the standard for fueling nuclear power reactors, according to the Arms Control Association. Adhering to it would extend the time it would take Iran to refine material to the 90% fissile purity needed for nuclear weapons. Currently, Iran could produce enough weapons-grade fissile material in one or two weeks, according to US officials.

While the ideas Witkoff presented in his Fox News interview were similar to the Obama administration's 2015 agreement allowing Iran to enrich uranium, they differed in other important aspects, experts said.

Witkoff appeared to suggest that the Trump administration wants Iran to permanently maintain its enrichment at levels no higher than 3.67%. The 2015 deal included a series of "sunset" provisions that allowed for increased enrichment levels over time. By 2031, Iran would be free to enrich to any purity level and increase its enrichment stockpile to any level.

Witkoff also suggested that a future agreement should include missiles that Iran might use to deliver a nuclear weapon. He said that verification procedures should include "the type of missiles they have stored there, including the bomb's trigger."

Iran has refused to negotiate its arsenal of ballistic and cruise missiles, which it considers essential to its status as a major regional power and a means of compensating for its relatively weak air force, which US intelligence said in its annual threat assessment last month suffers from outdated equipment and limited training.

Israeli Prime Minister Benjamin Netanyahu has consistently called for an agreement similar to the 2003 agreement with Libya, whose nuclear program was dismantled. Under the so-called Libyan model, Iran's nuclear program would be eliminated and its enrichment sites destroyed under US supervision.

Analysts say the course of the talks indicates a difference in views between the United States and Israel, its main ally in the region.

Trump has indicated that he strongly prefers a diplomatic solution to military action, in which Iran could attack US allies and forces in the region and disrupt oil traffic through the Strait of Hormuz, one of the world's most important commercial waterways.

But he continued to threaten Tehran with dire consequences if it did not quickly agree to a new nuclear agreement. Trump said on Monday that this could include a US attack on Iranian nuclear facilities—a direct threat that US officials have generally avoided.

"It's very simple. They can't have a nuclear weapon, and they have to move quickly, because they're very close to having one, and they won't have one," he said.

When asked if this included the possibility of striking Iranian nuclear facilities, the president replied, "Absolutely."

Iran has long stated that it requires 20% enriched uranium to operate its research reactor, a level well above the minimum proposed by Witkoff. It began producing material enriched to this level in 2010.

According to reports, Iran currently produces 60% highly enriched uranium, the only non-nuclear weapons state to do so. This material can be quickly converted into the 90% fissile material needed to make a bomb.

Given Iran's progress in manufacturing and installing more advanced centrifuges for uranium enrichment, a 3.67% limit could allow Iran to accumulate enough fissile material for a bomb within several months unless its stockpile is shipped out of the country. Under the 2015 agreement, Tehran remained 12 months away from the so-called breakout point during the first decade, but the breakout time has since been significantly reduced.

Even if Iran had enough material to build a weapon, it would still need to be converted into a nuclear device. US officials say it would take several months for Iran to produce a nuclear weapon.

Iran is working hard to overcome the remaining obstacles. US intelligence, in its threat assessment, noted that Iranian Supreme Leader Ayatollah Ali Khamenei has not authorized the development of a nuclear weapon, but is likely under increasing pressure to do so.

Khamenei said on Tuesday that the first steps in the nuclear talks had been implemented well.

"We are neither very optimistic nor very pessimistic about the talks," he said, according to Iranian media.

There are currently IAEA inspectors in Iran, but Tehran has imposed significant restrictions on their activities.