US Vice President JD Vance told Reuters that Tehran would need to make a meaningful reduction in its enrichment capacity rather than provide assurances that it would reduce nuclear activity at a later stage.
The demand represents a central obstacle to negotiations between Washington and Tehran. Iran and the United States have exchanged proposals in recent weeks aimed at ending the conflict and reopening the Strait of Hormuz, a critical route for global oil and liquefied natural gas shipments.
Vance said Washington remained open to an agreement but wanted concrete Iranian concessions. The United States has questioned Tehran's explanation for retaining uranium enriched to 60%, arguing that such material is inconsistent with claims that Iran's nuclear programme is intended solely for peaceful purposes.
A provisional peace agreement reached in June collapsed shortly afterwards, while US President Donald Trump has rejected Iran's latest proposal and warned that military operations could intensify after the November midterm elections.
The diplomatic process is further complicated by uncertainty over Iran's internal decision-making structure. Vance said Washington was communicating with President Masoud Pezeshkian and Foreign Minister Abbas Araqchi but remained uncertain about how much authority they exercise following the killing of Supreme Leader Ayatollah Ali Khamenei during the conflict.
Iran has rejected the US assessment, saying Washington understands the country's political system and accusing American officials of sending contradictory messages.
The conflict has already had significant economic consequences. The war is estimated to cost about $3 billion a month and has disrupted energy markets, while higher fuel prices have increased inflationary pressure across major economies.
For global markets, the outcome of the negotiations could determine whether energy flows through the Strait of Hormuz normalise or remain vulnerable to further disruption.
The talks therefore carry consequences extending beyond the nuclear dispute, with regional security, global energy prices and inflation increasingly tied to the prospects for a sustainable settlement.
