JD Vance said on Friday that the US wins “either way” regarding negotiations with Iran, pointing to what he called the destruction of its nuclear program and diminishment as a country.

“If we make the final deal, then great,” the US vice-president told HBO’s Bill Maher. “If we don’t make the final deal, their nuclear program is still destroyed. They’re still much weaker as a country, so my attitude is America wins either way.”

Vance said that the increased flow of oil through the strait of Hormuz was a “signal that there’s something real going on”.

But he acknowledged that the ceasefire deal between Donald Trump and the Iranian president, Masoud Pezeshkian, under a 60-day memorandum of understanding (MOU), “is always going to be a little messy when you’re dealing with the Iranians”.

Vance’s appearance on the politics-flavored comedy talkshow Real Time came hours before it was reported that a tanker was struck by a projectile in the strait and the US and Iran each launched strikes in the worst escalation since they signed the interim peace deal.

Washington said ​it hit Iranian targets overnight, while Iran said it had struck targets linked to US forces on Saturday in response. Saturday’s attack on a tanker followed an attack on a cargo ship on Thursday that triggered the hostilities.

Vance’s comments came during an appearance to promote his new memoir, Communion: Finding My Way Back to Faith, but most of the segment concerned foreign and domestic policy issues.

Vance said his negotiations with an Iranian delegation in Lucerne, Switzerland, have been successful because oil is “down to $73 a barrel” and Iran’s nuclear program was “functionally destroyed”, pointing to the country’s ability to enrich uranium.

Critics of the MOU and the ongoing negotiations say the Trump administration is negotiating with a weak hand in part because Iran still has a stockpile of 60%-enriched uranium, which may not accessible but remains in the country nevertheless.

The director general of the International Atomic Energy Agency (IAEA), Rafael Grossi, said on Friday that reducing Iran’s stockpile or transferring it abroad remains a viable option while the US and Iran pursue a comprehensive agreement.

Pressed by Maher on whether Iran’s nuclear program is destroyed, Vance shot back: “What part of it is not destroyed? The thing that you have to destroy is their ability to enrich uranium, which has been destroyed.”

He offered Iran an olive branch. “If they are willing to give up nuclear weapons ambitions for the long term, then the United States is willing to fundamentally transform our relationship with that country,” he said.

“If they’re willing to change, we’re willing to change too; if they’re not willing to change, we still fundamentally have all the cards and I think that’s a good place to be.”

Vance’s media appearance comes two days after he visited the Richard Nixon presidential library and museum in California, where he appeared to defend Nixon – who is celebrated by Republicans for negotiating landmark nuclear arms control deals with the Soviet Union – for the Watergate break-in scandal that ended his presidency.

“I think that his historical legacy is enjoying a bit of a renaissance – but I think deservedly so,” Vance said of Nixon, who also opened diplomatic relations with communist China and formed a Republican party allegiance with working-class Americans. “If Watergate happened tomorrow, it would be like a 12-hour news story. Like, the idea that it would have taken down a presidency is crazy.”

On Real Time, Vance sidestepped an effort by Maher to acknowledge that the administration’s immigration enforcement policies had gone too far. “You can’t do a law enforcement operation like that without having some situations that are recorded like that,” Vance said. “I don’t think there was an easy way to do this.”