The United States and Israel carried out military strikes on Iran on Saturday, targeting its top leaders and plunging the Middle East into a conflict that President Donald Trump said would end a security threat to the US and give Iranians a chance to topple their rulers.

Tehran responded by launching missiles at Israel and called the strikes against it unprovoked and illegal. Explosions also rang out in nearby oil-producing Gulf Arab countries, which said they had intercepted missiles after Tehran warned it would strike the region if it was attacked.

The first wave of strikes in what the Pentagon named “OPERATION EPIC FURY” mainly targeted Iranian officials, a source familiar with the matter said, two days after indirect talks mediated by Oman failed to produce a breakthrough on Iran's nuclear programme.

An Israeli official said Iranian Supreme Leader Ayatollah Ali Khamenei and President Masoud Pezeshkian were both targeted but the result of the strikes was not clear. A source with knowledge of the matter had earlier told Reuters that Khamenei was not in Tehran and had been transferred to a secure location.

An Iranian source close to the establishment said several senior commanders in Iran's Revolutionary Guards and political officials had been killed. Forty people were killed in an Israeli airstrike on a school, state media said. Reuters could not independently confirm the reports.

Trump says ‘Bombs will be dropping everywhere’

In a video message published on social media, Trump undefined cited Washington's decades-old dispute with Iran, including the seizure of the 1979 US embassy in Tehran, when students held 52 Americans hostage for 444 days, as well as a range of other attacks the US has blamed on Iran since the 1979 Islamic revolution brought the clerics to power.

Trump said the "massive" operation was intended to ensure Tehran does not obtain a nuclear weapon and aimed at "eliminating imminent threats from the Iranian regime".

He urged Iranians to stay sheltered because "bombs will be dropping everywhere". But he added: "When we are finished, take over your government. It will be yours to take. This will be probably your only chance for generations.”

Israeli Prime Minister Benjamin Netanyahu said the joint US-Israeli attack "will create the conditions for the brave Iranian people to take their destiny into their own hands" and "remove the yoke of tyranny". Defence Minister Israel Katz called it a pre-emptive strike to remove threats to Israel.

The attacks follow a 12-day air war last June between Israel and Iran, and US and Israeli warnings that they would strike again if Iran pressed ahead with its nuclear and ballistic missile programmes. The threats were backed up by a US military buildup in the region.

An Israeli defence official said the operation had been planned for months in coordination with Washington, and that the launch date was decided weeks ago.

Israel’s military said its Air Force had identified Iranian operatives in western Iran loading a missile unit and preparing to launch an attack. The Air Force struck the operatives and the launcher, preventing the attack, it said.

Missiles fired at Arab gulf states

The renewed confrontation dimmed hopes of a diplomatic solution to Tehran's nuclear dispute with the West.

Iran's Revolutionary Guards said all U.S. bases and interests in the region were within Iran's reach and that Iran's retaliation would continue until "the enemy is decisively defeated". Iraq's Iran-aligned armed group Kataib Hezbollah said it would soon attack US bases in the region.

Loud booms sounded in Abu Dhabi, capital of the United Arab Emirates, an oil producer and close US ally, and several blasts were heard in the business capital Dubai.

Bahrain said the service center of the US Fifth Fleet had been subjected to a missile attack. Video footage showed a thick grey plume of smoke rising from near the island state's coastline as sirens wailed.

Qatar said it had downed all missiles targeting the country and that it had a right to respond. Kuwait confirmed a missile attack on a US military base there.

Explosions were also heard near Iran's Kharg Island. Iran exports 90 percent of its crude oil via Kharg, for shipping through the narrow Strait of Hormuz.

In Israel, police said all holy sites were closed to visitors under national emergency guidelines after authorities announced several barrages of missiles were launched from Iran.

Global airlines cancelled flights across the Middle East and the attacks raised the prospect of oil prices rising. Some oil majors and trading houses suspended crude oil and fuel shipments via the Strait of Hormuz, four trading sources said.

"If we don’t see signs of de-escalation over the weekend, risk premiums could still drive Brent (crude) up by $10–$20/bbl (a barrel) on Monday," said Jorge Leon, head of geopolitical analysis at Rystad Energy.

Iranians rush to banks

The US and Iran renewed negotiations in February on the nuclear dispute, and Iran’s ballistic missile programme has been a significant sticking point, with Trump saying Tehran was developing long-range missiles that threaten the US.

Iran, which denies seeking atomic bombs, said it was prepared to discuss curbs on its nuclear programme in exchange for lifting sanctions but ruled out linking the issue to missiles.

In Tehran, witnesses said people were rushing to banks to withdraw cash. Long queues formed at gas stations across cities. Many also worried about a potential internet blackout that would cut off communication with their families abroad.

“We are being killed by the regime and by Israel. We are the victims of this regime’s hostile policies,” said Maryam, 54, a housewife in Tehran, as she headed to northern Iran with her family.

Israel's military did not immediately respond to a request for comment on the strike at a primary school for girls in southern Iran, where Iranian state media reported 40 deaths.