By JON GAMBRELL and JOSEF FEDERMAN Associated Press

JERUSALEM (AP) — Israel attacked Iran’s capital early Friday in strikes that targeted the country’s nuclear program and raised the potential for an all-out war between the two bitter Middle East adversaries. It appeared to be the most significant attack Iran has faced since its 1980s war with Iraq, with multiple sites around the country hit.

The leader of Iran’s paramilitary Revolutionary Guard was feared dead, Iranian state television reported, a development that would be a major body blow to Tehran’s governing theocracy and an immediate escalation of the nations’ long-simmering conflict. The report offered few details about what happened to Gen. Hossein Salami but said that another top Guard official, as well as two nuclear scientists, were also feared dead.

Israeli leaders said the attack was necessary to head off what they described as an imminent threat that Iran would build nuclear bombs, and they warned of a reprisal that could target civilians in Israel.

In Washington, the Trump administration, which earlier cautioned Israel against an attack amid continuing negotiations, said that it had not been involved in the attack and warned Iran against retaliations against U.S. interests or personnel.

Multiple sites in the capital were hit in the attack, which Israeli Prime Minister Benjamin Netanyahu said targeted both nuclear and military sites. Also targeted were officials leading Iran’s nuclear program and its ballistic missile arsenal.

The assault came amid warnings from Israel that it would not permit Tehran to build a nuclear weapon, though it remains unclear how close the country actually is to achieving that.

Netanyahu said in an address on YouTube that the attacks will continue “for as many days at it takes to remove this threat.”

The attack followed increasing tensions that led the U.S. to pull some diplomats from Iraq’s capital and to offer voluntary evacuations for the families of U.S. troops in the wider Middle East.

U.S. Secretary of State Marco Rubio said Israel took “unilateral action against Iran” and that Israel advised the U.S. that it believed the strikes were necessary for its self-defense.

“We are not involved in strikes against Iran, and our top priority is protecting American forces in the region,” Rubio said in a statement released by the White House that warned Iran against targeting U.S. interests or personnel.

The attack comes as tensions have reached new heights over Tehran’s rapidly advancing nuclear program.

The Board of Governors at the International Atomic Energy Agency for the first time in 20 years on Thursday censured Iran over its refusal to work with its inspectors. Iran immediately announced it would establish a third enrichment site in the country and swap out some centrifuges for more-advanced ones.

There are multiple assessments on how many nuclear weapons Iran could potentially build, should it choose to do so. Iran would need months to assemble, test and field any weapon, which it so far has said it has no desire to do. U.S. intelligence agencies also assess Iran does not have a weapons program at this time.

Benchmark Brent crude spiked on news of the attack, rising nearly 5%.

Israeli Defense Minister Israel Katz said that his country carried out the attack, without saying what it targeted.

“In the wake of the state of Israel’s preventive attack against Iran, missile and drone attacks against Israel and its civilian population are expected immediately,” he said in a statement.

The statement added that Katz “signed a special order declaring an emergency situation in the home front.”

“It is essential to listen to instructions from the home front command and authorities to stay in protected areas,” it said

Both Iran and Israel closed their airspace.

As the explosions in Tehran started, President Donald Trump was on the lawn of the White House mingling with members of Congress. It was unclear if he had been informed, but the president continued shaking hands and posing for pictures for several minutes.

Trump earlier said he was urging Netanyahu to hold off from taking action for the time being while the administration negotiated with Iran.

“As long as I think there is a (chance for an) agreement, I don’t want them going in because I think it would blow it,” Trump told reporters.