Israel pounded Iran for a fifth day in an air campaign against its longstanding foe’s military and nuclear programme, as US President Donald Trump warned residents of Tehran to evacuate and suggested the United States was working on something “better than a ceasefire.”

Trump left the Group of Seven summit in Canada a day early to deal with the conflict between Israel and Iran, telling reporters on Air Force One during the flight back to Washington: “I’m not looking at a ceasefire. We’re looking at better than a ceasefire.”

When asked to explain, he said the US wanted to see “a real end” to the conflict that could involve Iran “giving up entirely.” He added: “I’m not too much in the mood to negotiate.”

Trump’s cryptic messages added to the uncertainty roiling the region as residents of Tehran fled their homes in droves and the UN nuclear watchdog for the first time said Israeli strikes on Iran’s main enrichment facility at Natanz had also damaged its underground section, and not just the surface area.

Israel says its sweeping assault on Iran’s top military leaders, nuclear scientists, uranium enrichment sites and ballistic missile programme is necessary to prevent its adversary from getting any closer to building an atomic weapon. The strikes have killed at least 224 people in Iran.

Iran has retaliated by launching more than 370 missiles and hundreds of drones at Israel. So far, 24 people have been killed in Israel. The Israeli military said a new barrage of missiles was launched on Tuesday.

The International Atomic Energy Agency said on Tuesday it believes that Israel’s first aerial attacks on Iran’s Natanz enrichment site had “direct impacts” on the facility’s underground centrifuge halls.

“Based on continued analysis of high-resolution satellite imagery collected after Friday’s attacks, the IAEA has identified additional elements that indicate direct impacts on the underground enrichment halls at Natanz,” the watchdog said.

Located 220 kilometres (135 miles) southeast of Tehran, the Natanz facility was protected by anti-aircraft batteries, fencing and Iran’s paramilitary Revolutionary Guard.

The underground part of the facility is buried to protect it from airstrikes and contains the bulk of the enrichment facilities at Natanz, with 10,000 centrifuges that enrich uranium up to 5%, experts assess.

The IAEA had earlier reported that Israeli strikes had destroyed an above-ground enrichment hall at Natanz and knocked out electrical equipment that powered the facility.

However, most of Iran’s enrichment takes place underground.

Although Israel has struck Natanz repeatedly and claims to have inflicted significant damage on its underground facilities, Tuesday’s IAEA statement marked the first time the agency has acknowledged impacts there.

Iran maintains its nuclear programme is peaceful, and the United States and others have assessed Tehran has not had an organised effort to pursue a nuclear weapon since 2003. But the head of the IAEA has repeatedly warned that the country has enough enriched uranium to make several nuclear bombs should it choose to do so.

While Prime Minister Benjamin Netanyahu claimed on Tuesday that Israeli strikes on Iran’s nuclear sites have set the country’s nuclear programme back a “very, very long time,” Israel has not been able to reach Iran’s Fordo uranium enrichment facility, which is buried deep underground.

Echoing an earlier Israeli military call for some 330,000 residents of a neighbourhood in downtown Tehran to evacuate, Trump on Tuesday warned on social media that “everyone should immediately evacuate Tehran!”

Tehran is one of the largest cities in the Middle East, with around 10 million people, roughly equivalent to the entire population of Israel. People have been fleeing since hostilities began.

Asked why he had urged for the evacuation of Tehran, Trump said: “I just want people to be safe.”

Downtown Tehran appeared to be emptying out early on Tuesday, with many shops closed. The ancient Grand Bazaar was also closed, something that only happened in the past during anti-government demonstrations or at the height of the coronavirus pandemic.

On the roads out of Tehran to the west, traffic stood bumper to bumper. Many appeared to be heading to the Caspian Sea, a popular vacation spot where a large number of middle- and upper-class Iranians have second homes.

Long lines also could be seen at gas stations in Tehran. Printed placards and billboards calling for a “severe” response to Israel were visible across the city. Authorities cancelled leave for doctors and nurses, while insisting everything was under control.

The Israeli military meanwhile claimed to have killed someone it described as Iran’s top general in a strike on Tehran. Iran did not immediately comment on the reported killing of Gen Ali Shadmani, who had just been named as the head of the Khatam al-Anbiya Central Headquarters, part of the paramilitary Revolutionary Guard.

Iran has named other generals to replace the top leaders of the Guard and the regular armed forces after they were killed in earlier strikes.

Before leaving the summit in Canada, Trump joined the other leaders in a joint statement saying Iran “can never have a nuclear weapon” and calling for a “de-escalation of hostilities in the Middle East, including a ceasefire in Gaza.”

French President Emmanuel Macron told reporters that discussions were underway on a ceasefire between Israel and Iran, but Trump appeared to shoot that down in his comments on social media.

Macron “mistakenly said that I left the G7 Summit, in Canada, to go back to D.C. to work on a ‘cease fire’ between Israel and Iran,” Trump wrote. “Wrong! He has no idea why I am now on my way to Washington, but it certainly has nothing to do with a Cease Fire. Much bigger than that.”

Trump said he wasn’t ready to give up on diplomatic talks, and could send Vice President JD Vance and special envoy Steve Witkoff to meet with the Iranians.

“I may,” he said. “It depends on what happens when I get back.”

Israeli military spokesperson Brig. Gen. Effie Defrin said Monday his country’s forces had “achieved full aerial superiority over Tehran’s skies.”

The military said it destroyed more than 120 surface-to-surface missile launchers in central Iran, a third of Iran’s total, including multiple launchers just before they launched ballistic missiles towards Israel. It also destroyed two F-14 fighter planes that Iran used to target Israeli aircraft, the military said.

Israeli military officials also said fighter jets had struck 10 command centres in Tehran belonging to Iran’s Quds Force, an elite arm of its paramilitary Revolutionary Guard that conducts military and intelligence operations outside Iran.

Israel’s military issued an evacuation warning for a part of central Tehran that houses state TV and police headquarters, as well as three large hospitals, including one owned by the Guard. It has issued similar evacuation warnings for parts of the Gaza Strip and Lebanon ahead of strikes.

• An AP report