A powerful US bunker-busting bomb was used in combat for the first time when Washington struck Iranian nuclear sites this weekend.

Israel had carried out a week of air strikes on Iran, but does not possess the GBU-57 -- a 30,000-pound (13,600 kilogram) weapon viewed as necessary to reach the most deeply buried facilities -- or the aircraft needed to deploy it.

General Dan Caine, the top US military officer, told journalists on Sunday that Washington's forces dropped 14 of the bombs in the massive operation aimed at knocking out Tehran's nuclear program.

Aerial assaults raged between Iran and Israel early Monday, while Tehran vowed retaliation over the bunker-buster bombs American warplanes unleashed at the weekend on three nuclear sites.

US President Donald Trump insisted the attack had "obliterated" Iran's nuclear capabilities, but other officials said it was too soon to determine how significantly Tehran's nuclear programme had been impacted.

As the world awaited Iran's reply, supreme leader Ayatollah Ali Khamenei called the bombing campaign Israel launched on June 13 "a big mistake".

The United States has carried out strikes that caused "extremely severe damage" to three of Iran's nuclear facilities, the top US military officer, General Dan Caine, said on Sunday.

President Donald Trump had spent weeks pursuing a diplomatic path to replace the nuclear deal with Tehran that he tore up during his first term in 2018.

But he ultimately decided to take military action against Iran's nuclear program, which had already been bombarded in a more than week-long Israeli campaign that has also targeted Tehran's top military brass.

Israelis expressed relief and optimism Sunday after US President Donald Trump ordered air strikes on Iran, 10 days into a war that has widespread public support.

Despite daily nerve-shredding trips to bomb shelters and growing damage around the country, Israelis appeared united behind Prime Minister Benjamin Netanyahu's move to attack Iran on June 13.

Trump's decision to authorise overnight bombing raids on Iran's nuclear facilities has provided further reassurance after more than a week of sorties by the Israeli air force.

First responders fanned out across Israel Sunday following fresh waves of Iranian missile strikes that left pockets of devastation in their wake -- as the Islamic republic hit back after a US attack on its nuclear sites.

In both Haifa and areas around Tel Aviv, the scenes were all too similar.

Rubble filled streets at impact sites as the facades of apartment buildings were eviscerated by the falling projectiles, as rescue teams picked through the debris looking for people.

Three areas of Israel including coastal hub Tel Aviv were hit Sunday morning during waves of Iranian missile attacks, with at least 23 people injured, according to rescue services and police.

Several buildings were heavily damaged in the Ramat Aviv area in Tel Aviv, with holes torn in the facades of apartment blocks.

"Houses here were hit very, very badly," Tel Aviv mayor Ron Huldai told reporters at the scene. "Fortunately, one of them was slated for demolition and reconstruction, so there were no residents inside.

The US military attacked three sites in Iran on Sunday -- Natanz, Isfahan and the mountain-buried Fordo, all key parts of Tehran's nuclear programme, which it maintains is purely for civilian purposes.

American planes launched a "very successful attack", US President Donald Trump said, claiming Iran's main nuclear enrichment facilities had been "completely and totally obliterated".

Trump has said Tehran must never get a nuclear weapon, and ally Israel has claimed its attacks on Iran have set back the country's nuclear weapons progress by several years.

For nearly a half-century the United States has squabbled with Iran's Islamic Republic but the conflict has largely been left in the shadows, with US policymakers believing, often reluctantly, that diplomacy was preferable.

With President Donald Trump's order of strikes on Iran's nuclear sites, the United States -- like Israel, which encouraged him -- has brought the conflict into the open, and the consequences may not be clear for some time to come.

More than four months since his release from Gaza, former hostage Keith Siegel bears the mental scars of 484 days of captivity in destroyed buildings and tunnels in the hands of Palestinian militant group Hamas.

The 66-year-old Israeli-American and his wife Aviva were among 251 hostages seized from residential communities along the Gaza border, army bases and a music festival on October 7, 2023.

President Donald Trump delivered brief remarks from the White House late Saturday after the US military carried out strikes on Iranian nuclear sites.

Here is what Trump said in full:

"A short time ago the US military carried out massive precision strikes on the three key nuclear facilities in the Iranian regime: Fordo, Natanz and Isfahan.

"Everybody heard those names for years as they built this horribly destructive enterprise.