By ELENA BECATOROS Associated Press

ATHENS, Greece (AP) — The United States inserted itself into Israel’s war against Iran, bombing three of the Islamic Republic’s key nuclear sites overnight in an attack it dubbed “Operation Midnight Hammer.” U.S. President Donald Trump asserted that the sites were “completely and fully obliterated,” and warned there would be additional strikes if Iran retaliates.

The U.S. strikes came after a week of open conflict between Israel and Iran, sparked by Israel’s sudden barrage of attacks against Iran’s nuclear and military structure.

Israeli strikes began on June 13. Targeting Iranian military and nuclear sites, they killed several top military officials and nuclear scientists. Iran retaliated by firing hundreds of missiles and drones at Israel, some of which penetrated the country’s vaunted multi-tiered air defense system. The war so far has killed hundreds of people and wounded more than 1,000 in Iran and killed two dozen and wounded hundreds in Israel.

Iran insists its nuclear program is only for peaceful purposes. But Israel views it as an existential threat and has said its military campaign is necessary to prevent Iran from building an atomic weapon.

Although U.S. intelligence agencies have assessed that Tehran is not actively pursuing a bomb, Trump and Israeli leaders have argued it could quickly assemble a nuclear weapon, making it an imminent threat.

The region has been on edge for the past two years as Israel seeks to annihilate the Hamas militant group, an Iranian ally, in the Gaza Strip, where war still rages after Hamas’ Oct. 7, 2023, attack on southern Israel.

Here’s what to know about the conflict between Israel and Iran, and the United States’ intervention:

US bombs Iran

Trump announced the overnight “massive precision strikes” on Iran’s Fordo, Isfahan and Natanz nuclear sites in a televised address to the nation from the White House. Describing them as “a spectacular military success,” he said they had “completely and fully obliterated” the nuclear sites. Iran, he said, would now have to make peace.

The chairman of the Joint Chiefs of Staff, Air Force Gen. Dan Caine, said during a news briefing in Washington Sunday that while “final battle damage will take some time,” initial assessments indicated all three nuclear sites had been heavily damaged.

Defense Secretary Pete Hegseth said the strikes had not aimed at toppling the Iranian government.

“This mission was not and has not been about regime change,” Hegseth said during the news briefing.

Iran’s Atomic Energy Organization confirmed the attacks, but insisted its nuclear program will not be stopped. Iran and the U.N. nuclear watchdog agency said there were no immediate signs of radioactive contamination at the three locations following the strikes.

The nuclear fuel enrichment site at Fordo is buried deep beneath a mountain, and the attack against it used bunker-buster bombs designed to penetrate the ground before exploding, a U.S. official said, speaking on condition of anonymity to discuss military operations. Only the United States has the 30,000-pound (13,600-kilogram) munition and the stealth bombers used to deliver them.

Trump warned there would be additional strikes if Tehran retaliated against U.S. forces, while Israeli Prime Minister Benjamin Netanyahu praised Trump’s decision to attack.

Iran’s response

Iran launched a barrage of missiles against Israel overnight and into Sunday, with Israeli authorities reporting that more than 80 people were wounded, the vast majority of them lightly.

Iran’s Foreign Minister Abbas Araghchi said the time for diplomacy had passed and his country had the right to defend itself.

“The warmongering, a lawless administration in Washington is solely and fully responsible for the dangerous consequences and far-reaching implications of its act of aggression,” he said in a news conference in Istanbul. “They crossed a very big red line by attacking nuclear facilities.”

How Tehran might retaliate remains unclear, but an Iranian response could mean a wave of attacks on U.S. forces in the Middle East, an attempt to close a key bottleneck for global oil supplies or a dash to develop a nuclear weapon.

‘A dangerous escalation’

U.N. Secretary-General Antonio Guterres said he was “gravely alarmed” by the United States’ use of force, and called the strikes a “dangerous escalation.” World leaders issued calls for diplomacy.

“There is a growing risk that this conflict could rapidly get out of control — with catastrophic consequences for civilians, the region and the world,” Guterres said in a statement on X. “I call on Member States to de-escalate.”

The European Union’s foreign policy chief, Kaja Kallas, said Iran must not be allowed to develop a nuclear weapon, but urged restraint.

“I urge all sides to step back, return to the negotiating table and prevent further escalation,” she said in a social media post. Kallas will chair a meeting of the 27-nation bloc’s foreign ministers in Brussels on Monday, with the Israel-Iran war high on the agenda.

Iranian-backed Houthi rebels in Yemen, who had threatened to resume attacks on U.S. vessels in the Red Sea if the Trump administration joined Israel’s military campaign, called on other Muslim nations to form “one front against the Zionist-American arrogance.”

Iranian Supreme Leader Ayatollah Ali Khamenei had warned the U.S. on Wednesday that strikes against Iran would “result in irreparable damage for them.”

The Israeli military said Saturday it was preparing for the possibility of a lengthy war, while Iran’s foreign minister warned before the U.S. attack that American military involvement “would be very, very dangerous for everyone.”