The renewed diplomatic push to end the United States-Israel war on Iran is facing headwinds as Tehran’s nuclear programme, which the two countries invoked to launch the war in February, has once again emerged as one of the biggest stumbling blocks in reaching a ceasefire.

Nearly eight months into the war, which has caused a global energy crisis, a deal to ensure a permanent ceasefire remains elusive. Moreover, the war has since spilled into a regional conflict, with Yemen emerging as its latest theatre.

The reopening of the Strait of Hormuz – a global oil chokepoint – was the focus of the June Memorandum of Understanding (MoU) signed between the US and Iran.

The MoU had also stated that Iran “shall not procure or develop nuclear weapons”, but a comprehensive deal, including the nuclear issue, could not be thrashed out within the stipulated 60-day period. Analysts said that differing interpretations of the agreement clauses caused the MoU to fall apart.

Now the nuclear issue has once again emerged as the central point of contention, with Tehran insisting that uranium enrichment is a right guaranteed under the Non-Proliferation Treaty (NPT).

US President Donald Trump, on the other hand, has called for “zero uranium enrichment”. His ally, Israeli Prime Minister Benjamin Netanyahu, on Sunday reiterated his pledge to topple the Iranian government, which he said is key to preventing it from developing nuclear weapons.

Earlier this week, US Vice President JD Vance appeared to offer concessions on the nuclear doctrine to reach a deal.

While Qatar and Pakistan are engaged in mediation efforts, how will they get the sides to agree on the nuclear enrichment issue?

This handout picture provided by the Iranian presidency shows Iran’s President Masoud Pezeshkian receiving Pakistan’s army chief Asim Munir in Tehran on October 20, 2026 [Handout/Iranian presidency via AFP] What is Iran saying?

Pakistan’s army chief Asim Munir, who is also a key negotiator in the conflict, is currently in Tehran, where he met Iran’s security chief Mohsen Rezaei on Tuesday.

In the meeting, Rezaei said “even a particle of enriched uranium will not exit Iran at all,” according to comments carried by Iran’s semi-official Fars news agency, describing the material as a major national asset that would remain in the country for domestic use.

His response came amid media reports that the US wants Iran to transfer part of its enriched uranium out of the country. Trump has previously called for the removal of the enriched uranium stockpile from Iran.

Rezaei also said negotiations with the US would not begin until Washington fulfils trust-building measures, including meeting the latest conditions Iran has set.

Iran wants the US to lift its naval blockade of Iranian ports, waive sanctions, and release frozen Iranian assets as part of its latest terms to end the war. In return, Iran has promised to reopen the Strait of Hormuz.

Another Iranian lawmaker, Alaeddin Boroujerdi, also a member of the Iranian parliament’s National Security and Foreign Policy Committee, reiterated that Iran is not seeking the production of nuclear weapons.

“Iran’s enrichment activities are unrelated to the US, and Washington should focus on fulfilling its own obligations regarding nuclear arms reduction,” he said.

US President Donald Trump speaks in the Oval Office, with Vice President JD Vance and Secretary of State Marco Rubio standing behind him, at the White House in Washington, DC [File: Kylie Cooper/Reuters] Where does the US stand?

Addressing a Republican Party campaign rally earlier this week, Trump claimed that the US bombing had destroyed Iran’s nuclear facilities and that he would not allow Tehran to rebuild them.

“They cannot have a nuclear weapon,” Trump told his supporters at a rally at Northern Kentucky University.

Vice President Vance said earlier this week that the US has “in some ways decisively won” the war on Iran and has destroyed the country’s nuclear programme.

He told a town hall hosted by CBS News that the US was now focused on ensuring that Iran makes a “long-term” and “verifiable commitment” not to rebuild its nuclear programme.

“Not over the administration of Donald Trump … but five years from now, could the Iranians rebuild that nuclear arsenal? Could they try to rebuild that enrichment capacity?” he asked.

US Secretary of State Marco Rubio also said this week that a decision to end the war finally rests with Trump. “The US will not support any deal that creates a pathway for Iran to have a nuclear weapon. As long as President Trump is in office, they will not have a nuclear weapon,” he reiterated.

Last month, Vance told the Reuters news agency in an interview that Tehran must make a “meaningful” reduction in its nuclear enrichment capacity to satisfy US demands and end the war.

“If you don’t want a nuclear weapon, then why do you need 60 percent enriched fuel? And if you want to show commitment to not building a nuclear weapon, don’t build highly enriched fuel. That’s a very basic threshold issue,” Vance said.

“I think if they want to show a commitment to not building a nuclear weapon, they would do something meaningful on their enrichment capacity,” he added.

What the MoU says about Iran’s uranium programme The MoU signed on June 17 left the future of Iran’s enriched uranium stockpile to further negotiations, but identified downblending under international supervision of the International Atomic Energy Agency as the minimum approach to resolving the issue.

Downblending involves mixing highly enriched uranium with lower-enriched material, making it less suitable for rapid conversion into weapons-grade material.

The MoU left room for Iran to reduce the material’s enrichment domestically rather than surrender it. However, it did not specify the quantity to be downblended, a target enrichment level or a detailed implementation timetable.

“The two parties also agreed to discuss the issue of enrichment and other mutually agreed matters related to the Islamic Republic of Iran’s nuclear needs, based on a satisfactory framework being agreed upon in the final deal,” the MoU clause reads. That final deal, of course, could not be reached as the MoU expired in mid-August.

The Trump administration invoked the imminent threat of Iran acquiring nuclear weapons to launch the war on February 28, 2026. On the first day of the war, US-Israel strikes killed Supreme Leader Ayatollah Ali Khamenei, who had banned the development of nuclear weapons in a fatwa, or religious edict.

President Trump has often argued that Iran would use the nuclear weapon “within moments after getting it”, and then “the Middle East would be gone, Israel would be gone, and then hit Europe probably next.”The US president has spoken out against Iran’s nuclear programme numerous times in the past.

As the war progressed over months, the US focus shifted gradually towards reopening the Strait of Hormuz as a base condition of the ongoing fighting.

Speaking in Alaska last week, Trump again falsely claimed that he had to start his war on Iran because, “[Iran was] two weeks away from having a nuclear weapon.”

In April, Trump had warned that “the enriched material, sometimes referred to as ‘Nuclear Dust,’ will be unearthed by the United States … and DESTROYED.”Later in the month, he told reporters on board Air Force One that the US would “go in with Iran, and we will take it together, and we will bring it back. 100 percent of it back to the United States.”

Mostafa Najafi, a foreign policy analyst based in Iran, noted that “despite [the US’s] insistence on nuclear negotiations and obtaining tangible concessions in this area, [Washington is] unwilling to offer significant concessions such as lifting sanctions.”

The US wants “to secure major concessions solely in exchange for lifting the blockade and releasing some of Iran’s assets”, he wrote in a post on X. “From Iran’s perspective, lifting the blockade and releasing assets is no longer a noteworthy concession for Tehran!”