In an interview, Vance said any agreement would require Iran to take concrete steps to reduce its enrichment capability rather than simply provide assurances about future limits.

He questioned why Iran would need uranium enriched to 60% if it did not intend to develop a nuclear weapon, saying Tehran would need to demonstrate its commitment through meaningful changes to its enrichment programme.

“If they want to show a commitment to not building a nuclear weapon, they would do something meaningful on their enrichment capacity,” Vance said.

Iran and the United States have exchanged proposals in recent weeks aimed at ending the conflict and reopening the Strait of Hormuz, a major global energy shipping route.

US President Donald Trump rejected Iran’s latest proposal and has warned that military operations could intensify after the US midterm elections.

Vance said Washington remained open to an agreement but would require concrete Iranian nuclear concessions.

“We’re not going to trade words for actions,” he said.

Uncertainty over Iran’s decision-making

Vance also said Washington remained uncertain about who ultimately makes decisions in Tehran.

He said the US was communicating with Iranian President Masoud Pezeshkian and Foreign Minister Abbas Araqchi but questioned how much authority they hold within Iran’s power structure.

Vance said the uncertainty had become more pronounced after US-Israeli strikes at the beginning of the war killed Supreme Leader Ayatollah Ali Khamenei.

Iranian Foreign Ministry spokesperson Esmaeil Baghaei rejected the suggestion that Washington was unaware of Iran’s decision-making structure, saying the real problem was contradictory positions and mixed messages from US officials.

Vance said he had spoken with military commanders to assess conditions on the battlefield. He also dismissed concerns about critical US munitions shortages.

He said Iranian forces had periodically managed to strike commercial ships in the Strait of Hormuz but had largely failed to prevent energy exports through the waterway.

Vance declined to say whether he was leading the peace negotiations, saying he was involved but that Trump was ultimately directing the process.

War becomes US political issue

The conflict, which Vance said was costing about $3 billion a month, has also become an issue in the US midterm election campaign.

Higher energy prices have increased political pressure on Trump and Republicans in closely contested states, with the cost of living becoming a major campaign issue.

Vance was in Alaska supporting Republican Senator Dan Sullivan, who is facing Democratic challenger Mary Peltola in a closely contested race.

Vance, who is regarded as a potential Republican presidential contender for 2028, said he had not decided whether to seek the presidency.

“I really haven’t thought about it much,” he said.