President Trump announced on Saturday that the U.S. military had “totally obliterated” three of Iran’s nuclear sites, including its uranium-enrichment facility deep underground at Fordo, injecting the United States directly into a war in the Middle East.

Neither Mr. Trump nor the Pentagon immediately provided evidence of his claim to have wiped out infrastructure that Israel’s leadership has long said could soon produce a nuclear weapon. And even as the president celebrated what he called “a spectacular military success,” he urged Iran to agree to peace terms or face further assaults.

Mr. Trump spoke for roughly four minutes, hours after he announced on social media that U.S. forces had hit the facilities. B-2 bombers dropped at least six 30,000-pound bunker busters on Fordo, and submarines fired 30 TLAM cruise missiles at Natanz and Isfahan, according to a U.S. official who spoke on the condition of anonymity to discuss military operations.

“Our objective was the destruction of Iran’s nuclear enrichment capacity,” Mr. Trump said in his televised address, flanked by Vice President JD Vance, Secretary of State Marco Rubio and Defense Secretary Pete Hegseth.

Mr. Trump also warned Iran’s leaders that they “must now make peace” — a demand he previously framed as “unconditional surrender.” Should they refuse to submit, he suggested, much more of Iran could be soon wiped out by Israel and the United States.

“There will be either peace or there will be tragedy for Iran, far greater than we have witnessed over the last eight days,” he said. “Remember, there are many targets left. Tonight’s was the most difficult of them all, by far, and perhaps the most lethal. But if peace does not come quickly, we will go after those other targets with precision, speed and skill. Most of them can be taken out in a matter of minutes.”

Mr. Trump, who campaigned on a promise to keep America out of foreign wars, has privately portrayed these strikes as a limited action, one adviser said. But the fact that he also threatened further attacks shows how armed conflict is rarely clean or predictable, as America’s long and costly engagements in Iraq and Afghanistan proved.

Iran’s leaders have promised to retaliate against America if it joined Israel in the war, and Iran’s missiles are within range of American military bases and other interests in the region.

Despite past differences with Prime Minister Benjamin Netanyahu of Israel, Mr. Trump thanked and congratulated him in his speech, saying that “we worked as a team like perhaps no team has ever worked before.” His remarks amounted to a tight embrace of Israel after months of mistrust and equivocation over whether to join Mr. Netanyahu’s military campaign.

The bombing came two days after White House officials said Mr. Trump would make a decision “within the next two weeks” about whether to move ahead with such an attack. Israeli officials were told about the bombing beforehand, and Mr. Trump spoke with Mr. Netanyahu afterward, according to a person with knowledge of the conversations who spoke on the condition of anonymity because they were not authorized to speak publicly.

Mr. Netanyahu praised Mr. Trump after the attacks. “History will record that President Trump acted to deny the world’s most dangerous regime the world’s most dangerous weapons,” he said.

Since signaling that he was considering striking Iran, around a week ago, Mr. Trump has faced pressure from Republican critics and supporters of such a move, highlighting a split within his own party.

Some advisers tried to dissuade him from carrying out a bombing raid. Others, accepting that he appeared determined to bomb the nuclear facilities, channeled their efforts into ensuring he had a full picture of the potential fallout from such an attack and to limit America’s involvement after the initial strikes.

Mr. Vance has warned against the potential of an Israeli-led war aimed at regime change in Iran, and Mr. Trump has told advisers and associates in recent days that he has no interest in joining a prolonged battle to topple Iran’s leadership.

Congressional Democrats and at least one House Republican were livid that Mr. Trump had not sought congressional approval before moving forward. The two top Republicans in the Senate and the House said they were alerted to the strikes before they happened.

Mr. Trump has said repeatedly that he does not want to send American troops into combat overseas. Even after Israel began its bombing campaign, Mr. Trump was encouraging Mr. Vance and his Mideast envoy, Steve Witkoff, to pursue diplomacy with Iran. The president has expressed frustration at Iranian officials and their slowness to respond to messages. And his team has complained that it is hard to know whether their Iranian interlocutors are speaking with any authority on behalf of the country’s supreme leader.

Now, the Trump administration is bracing for possible retaliation from Iran.

If Iran kills any Americans in its retaliatory attacks, Mr. Trump would be under pressure to respond with still more force, beginning a potential cycle of escalation. Anticipating such attacks, Mr. Trump posted a threatening message in all-caps on Truth Social soon after he finished speaking on Saturday night: “ANY RETALIATION BY IRAN AGAINST THE UNITED STATES OF AMERICA WILL BE MET WITH FORCE FAR GREATER THAN WHAT WAS WITNESSED TONIGHT.”

Earlier this year, Mr. Trump at least once waved Mr. Netanyahu off an attack on Iran. But in May, U.S. intelligence showed that Israel planned to strike Iran, with or without support from the Trump administration. In the weeks that followed, senior Trump officials developed options for the president, anticipating that they might soon be forced to respond to a unilateral Israeli strike.

Mr. Netanyahu told Mr. Trump in a June 9 phone call that he was determined to move ahead, and laid out the contours of Israel’s military plan. Mr. Trump, who had been pushing for a nuclear deal with Iran for months, quietly agreed to provide support from the intelligence community. But when Israel began its airstrikes on Iran on June 13, it was still unclear whether Mr. Trump would publicly embrace its mission.

The first statement from the administration after the Israeli strikes began came under Mr. Rubio’s name, distanced America from the war and made no mention of standing with Israel — an extraordinary omission for an American administration.

But by the next morning in the United States, when it appeared that Israel’s first night of attacks had been a success, Mr. Trump began claiming credit for the operation and hinting to reporters that he had more to do with the mission than people realized. That weekend, as he prepared to leave for Canada for the Group of 7 Summit, Mr. Trump told an associate privately that he might need to drop “the big one.” He was referring to the 30,000-pound bunker-busting bombs, carried by B-2 bombers, that Israel wanted, but only the U.S. military possessed.

Mr. Trump built his political career in part on his denouncement of the war in Iraq following the deadly terrorist attacks in the United States on Sept. 11, 2001. Yet one of his proudest moments of his first term was the assassination of the Gen. Qassim Suleimani of Iran, an act that alienated some of his staunchest anti-interventionist supporters but that he repeatedly maintained was necessary and in the national interest.

In his address on Saturday night, Mr. Trump referenced Mr. Suleimani as he described the dangers Iran presents.

“For 40 years, Iran has been saying, ‘Death to America, death to Israel,’” he said, adding: “I decided a long time ago that I would not let this happen. It will not continue.”

Eric Schmitt contributed reporting.