Israel attacked Iran early Friday with a barrage of airstrikes that took out top military officers and hit nuclear and missile sites, calling it just the beginning and raising 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.

Iran quickly retaliated, sending a swarm of drones at Israel as Supreme Leader Ayatollah Ali Khamenei warned of “severe punishment.” Iran had been censured by the U.N.'s atomic watchdog a day earlier for not complying with obligations meant to prevent it from developing a nuclear weapon.

For years, Israel had threatened such a strike and successive American administrations had sought to prevent it, fearing it would ignite a wider conflict across the Middle East and possibly be ineffective at destroying Iran’s dispersed and hardened nuclear program.

Countries in the region condemned Israel's attack, while leaders around the globe called for immediate deescalation from both sides.

Israel's military said about 200 aircraft were involved in the initial attack on about 100 targets. Two security officials said the country's Mossad spy agency was also able to position explosive drones inside Iran ahead of time and then activate them to target missile launchers at an Iranian base near Tehran.

They said Israel had also smuggled precision weapons into central Iran as well as strike systems on vehicles, which were activated as the attack began to hit Iranian air defenses.

The officials spoke on condition of anonymity to discuss the highly secretive missions and it was not possible to independently confirm their claims. There was no official comment.

The Israeli attack hit several sites, including Iran's main nuclear enrichment facility at Natanz, where black smoke could be seen rising into the air. Later in the morning, Israel said it had also destroyed dozens of radar installations and surface-to-air missile launchers in western Iran.

Israel military spokesman Brig. Gen. Effie Defrin said Israel has “significantly damaged” Natanz and that the operation was “still in the beginning.”

Among those killed were three of Iran’s top military leaders, one who oversaw the entire armed forces, Gen. Mohammad Bagheri, one who led the paramilitary Revolutionary Guard, Gen. Hossein Salami, and another who ran the Guard’s ballistic missile program, Gen. Amir Ali Hajizadeh.

Iran confirmed all three deaths, which were a significant blow to Tehran’s governing theocracy and will complicate efforts to retaliate against Israel.

Khamenei said other top military officials and scientists were also killed.

In its first response, Iran fired more than 100 drones at Israel. Israel said the drones were being intercepted outside its airspace, and it was not immediately clear whether any got through.

U.S. President Donald Trump urged Iran to reach a deal with Washington on its nuclear program, warning on his Truth Social platform that Israel’s attacks “will only get worse.”

Without saying whether he was privy to specific Israeli plans, Trump said “there is still time to make this slaughter, with the next already planned attacks being even more brutal, come to an end.”

“Iran must make a deal, before there is nothing left, and save what was once known as the Iranian Empire,” he wrote. “No more death, no more destruction, JUST DO IT, BEFORE IT IS TOO LATE.”

Officials in Washington had cautioned Israel against an attack during continued negotiations over Iran's nuclear enrichment program. They stressed the U.S. had not been involved and warned against any retaliation targeting U.S. interests or personnel.

Israel told the Trump administration that large-scale attacks were coming, U.S. officials said on condition of anonymity to describe private diplomatic discussions. On Wednesday the U.S. pulled some American diplomats from Iraq’s capital and offered voluntary evacuations for the families of U.S. troops in the wider Middle East.

Israeli leaders cast the attack as necessary to head off an imminent threat that Iran would build nuclear bombs, though it remains unclear how close the country is to achieving that or whether Iran had actually been planning a strike. Iran maintains its nuclear program is for civilian purposes only.

"This is a clear and present danger to Israel’s very survival,” Israeli Prime Minister Benjamin Netanyahu claimed as he vowed to pursue the attack for as long as necessary to “remove this threat.”

Over the past year, Israel has been targeting Iran’s air defenses, hitting a radar system for a Russian-made air defense battery in April 2024 and surface-to-air missile sites and missile manufacturing facilities in October.

Israelis rushed to supermarkets in Tel Aviv, Jerusalem and elsewhere to buy bottled water and other supplies, and circulated messages on WhatsApp groups advising each other to prepare their shelters for potential long-term use.

Khamenei said in a statement that Israel “opened its wicked and blood-stained hand to a crime in our beloved country, revealing its malicious nature more than ever by striking residential centers.”

For Netanyahu, the operation distracts attention from Israel’s ongoing and increasingly devastating war in Gaza, which is now over 20 months old.

There is a broad consensus in the Israeli public that Iran is a major threat, and Israel’s opposition leader, Yair Lapid, a staunch critic of Netanyahu, offered his “full support” for the mission against Iran. But if Iranian reprisals cause heavy Israeli casualties or major disruptions to daily life, public opinion could shift quickly.

The Iran-backed Lebanese militant group Hezbollah issued a statement that offered condolences and condemned the attack, but did not threaten to join Iran in its retaliation. Hezbollah’s latest war with Israel — which killed much of the group’s senior leadership — ended with a U.S.-brokered ceasefire in November.

Netanyahu expressed hope the attacks would trigger the downfall of Iran’s theocracy, saying his message to the Iranian people was that the fight was not with them, but with the “brutal dictatorship that has oppressed you for 46 years.”

“I believe that the day of your liberation is near,” he said.

In addition to targeting nuclear and military sites, Israel aimed its attacks at officials leading Iran’s nuclear program and its ballistic missile arsenal. The International Atomic Energy Agency confirmed that an Israeli strike hit Iran’s uranium enrichment facility at Natanz and said it was closely monitoring radiation levels.

The strike on Iran pushed the Israeli military to its limits, requiring the use of aging air-to-air refuelers to get its fighter jets close enough to attack. It wasn’t immediately clear if Israeli jets entered Iranian airspace or just fired so-called “standoff missiles” over another country. People in Iraq heard fighter jets overhead at the time of the attack.

The potential for an attack had been apparent for weeks as angst built over Iran's nuclear program.

Once the attacks were underway, the U.S. Embassy in Jerusalem issued an alert telling American government workers and their families to shelter in place until further notice.

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.

Trump is scheduled to attend a meeting of his National Security Council on Friday in the White House Situation Room.

Israel has long been determined to prevent Iran from developing nuclear weapons, a concern laid bare on Thursday when the Board of Governors at the International Atomic Energy Agency for the first time in 20 years censured Iran over its refusal to work with its inspectors. Iran immediately announced it would establish a third enrichment site and install more advanced centrifuges.

Even so, there are multiple assessments on how many nuclear weapons Iran could conceivably 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.

In a sign of the far-reaching implications of the emerging conflict, Israel's main airport was closed and benchmark Brent crude spiked on news of the attack, rising nearly 8% before retreating slightly.