“None of your business” is the Islamic Republic’s response to a request by the International Atomic Energy Agency’s inspectors to visit a suspected undeclared nuclear installation, putting into question the utility of an American-Iranian deal.

“I don’t think you can have a deal if Iran is not willing to cooperate with the IAEA and tell it what is going on,” a former inspector with the agency, David Albright, tells the Sun. The latest dispute between Iran and the agency emanates from a satellite image published by Mr. Albright’s think tank, the Institute for Science and International Security, that shows a tunnel next to the Natanz nuclear facility.

While visiting Iran last week, the IAEA chief, Rafael Grossi, asked the Iranians to explain the construction disclosed by Mr. Albright’s group, known as the Good ISIS. “We’re asking them, ‘What is this for?’ They are telling us, ‘It’s none of your business,’” Mr. Grossi said at Washington Wednesday.

As seen in the satellite images, the tunnel is directly next to the Natanz nuclear facility, which Iran allows the IAEA to inspect. The newly discovered construction, though, possibly leads to a secret installation under a mountain near that plant. “It’s completely obnoxious that they say it’s none of your business,” Mr. Albright says.

“What that implies to me,” he says, “is that maybe there is a gas centrifuge plant that they’re either building, or thinking about building, under that mountain, in addition to the centrifuge assembly facility” at Natanz. Either way, a refusal to allow access to the inspectors “gets right to the heart of the mission of the IAEA,” he adds.

Any inspection depends on knowledge of the “baseline” — an inventory of Iran’s current and past nuclear activities. Without knowing what the Iranians already have, it would be impossible to verify that, as President Trump puts it, “Iran can’t have a nuclear weapon.” 

Tehran’s foreign minister, Abbas Araghchi, has dismissed the Good ISIS discovery as a product of war mongers. “The attempts by the Israeli regime and certain Special Interest groups to derail diplomacy—using variety of tactics—is abundantly clear for all to see,” he wrote on X Wednesday.

“Those seeking to manipulate public opinion can also be expected to come up with fantastical claims and props like scary-looking satellite images,” Mr. Araghchi, who leads the Iranian team of negotiators, writes. “Reality check: Every single milligram of enriched uranium in Iran is under full and constant IAEA supervision and monitoring.”

Mr. Grossi has long reported incidents that contradict that statement, which could complicate attempts to reach a deal. This week’s postponement of a meeting of American and Iranian teams to Saturday from Wednesday “indicates there are some difficulties,” the top Iran watcher at the Middle East Media Research Institute, Ayelet Savyon, tells the Sun.

Iranians are “confused about the American positions,” she says. One growing concern at Tehran is Mr. Trump’s posting this week on Truth Social following a phone conversation with Prime Minister Netanayahu. “We are on the same side of every issue,” the president wrote, and “the Iranians are wondering what Trump meant,” Ms. Savyon says.

The Israeli premier has long indicated that a military option might be more effective than diplomacy in ending the Islamic Republic’s nuclear pursuit. Mr. Trump, in contrast, is promoting the idea of reaching a deal, even as he keeps the military threat alive. 

“I think we’re doing very well with respect to Iran,” Mr. Trump said Thursday. “We’re having very serious meetings, and there are only two options, and the one option is not a good option.” The president “desires to bring peace, and establish peace, and protect peace,” Secretary Rubio added. “That’s why we’re talking to Iran.”

In an interview with the Free Press this week, though, Mr. Rubio was forced to clean up after the top American negotiator, Steven Witkoff, earlier said that Iran would be allowed to domestically enrich uranium at a low level of 3.67 percent. What he referred to, Mr. Rubio said, was “the level of enriched material that they would be allowed to import from outside.”

Mr. Witkoff’s original statement muddled America’s opening positions, and Mr. Rubio “was mopping the floor of the mess Witkoff created, trying to put a happy spin on it,” Mr. Albright says. 

Tehran, though, will never give up the right to enrich, Ms. Savyon says. The Iranians, she adds, claim that in the leadup to the 2015 nuclear agreement, President Obama promised in writing that they could have a domestic enrichment program. 

A new agreement, then, might be elusive, possibly leading to a confrontation. “The Iranian regime top fear is an attack that would result in its demise,” according to Ms. Savyon. “Perhaps rather than striking nuclear facilities, the best option is to militarily strike at the regime.”

Correction: Ayelet Savyon is the name of the top Iran watcher at the Middle East Media Research Institute. An earlier version contained a spelling error.