Israel launched a retaliatory strike on Iran less than a week after Tehran's rocket and drone barrage, according to two U.S. officials.
An explosion was heard early today in Iran's central city of Isfahan, the country's semiofficial Fars news agency reported.
Two Israeli defense officials confirmed that the Israeli military was behind the strike while three Iranian officials had confirmed that a strike hit a military air base near Isfahan. The scale of the attack was unclear.
It remained unclear whether the country was under attack, as no Iranian official directly acknowledged the possibility and Israel's military did not respond to a request for comment. However, tensions have remained high in the days since the Saturday assault on Israel amid its war on Hamas in the Gaza Strip and its own strikes targeting Iran in Syria.
All the officials spoke on condition of anonymity because they were not authorized to discuss it publicly.
Flights were suspended in Isfahan and the Iranian cities of Tehran and Shiraz as well as airports across the country's western borders, Iran's Mehr news agency also reported.
Air defense batteries fired in several provinces after drones were reported in the air, state television reported.
In particular, IRNA said air defenses fired at a major air base in Isfahan, which long has been home to Iran's fleet of American-made F-14 Tomcats -- purchased before the 1979 Islamic Revolution.
The details of the blast in Isfahan are unknown, according to Fars, but the city -- home to several military bases and facilities -- is believed to have been one of several launch sites for Iran's April 13 attack.
Fars and the other semiofficial news agency Tasnim reported the sound of blasts, without giving a cause. State television acknowledged "loud noise" in the area.
Tasnim later published a video from one of its reporters, who said he was in the southeastern Zerdenjan area of Isfahan, near its "nuclear energy mountain." The footage showed two different anti-aircraft gun positions, and details of the video corresponded with known features of the site of Iran's Uranium Conversion Facility at Isfahan.
"At 4:45, we heard gunshots. There was nothing going on," he said. "It was the air defense, these guys that you're watching, and over there too."
The facility at Isfahan operates three small Chinese-supplied research reactors, as well as handling fuel production and other activities for Iran's civilian nuclear program.
Isfahan also is home to sites associated with Iran's nuclear program, including its underground Natanz enrichment site, which has been repeatedly targeted by suspected Israeli sabotage attacks.
State television described all sites in the area as "fully safe."
Dubai-based carriers Emirates and FlyDubai began diverting around western Iran about 4:30 a.m. local time. They offered no explanation, though local warnings to aviators suggested the airspace may have been closed.
Iran later announced it grounded commercial flights in Tehran and across areas of its western and central regions. Loudspeakers informed customers of the strike at Imam Khomeini International Airport in Tehran, online videos purported to show. Iran later restored normal flight service, authorities said.
Hossein Dalirian, a spokesman for Iran's civilian space program, said on X, formerly know as Twitter, that several small "quadcopter" drones had been shot down. A state television reporter in Isfahan said the same in a live report, saying "several small drones were flying in the sky over Isfahan, which were fired at."
Meanwhile in Iraq, where a number of Iranian-backed militias are based, residents of Baghdad reported hearing sounds of explosions, but the source of the noise was not immediately clear.
Israeli officials had notified the U.S. earlier Thursday that they planned to retaliate in the next 24-48 hours, according to two U.S. officials who asked not to be identified discussing private conversations. Spokespeople for the National Security Council and the Pentagon declined to comment.
The reports come after Israel vowed to retaliate against Iran for its barrage of 300 drones and missiles. Iran said it was responding to a strike on its diplomatic building in Syria that killed several Iranian officers on April 1.
U.S. Defense Secretary Lloyd Austin spoke with Israeli Defense Minister Yoav Gallant on Thursday, Pentagon spokesman Pat Ryder said in a statement before the strikes were reported.
The two men discussed "regional threats and Iran's destabilizing actions in the Middle East," Ryder said. The statement didn't say whether Gallant gave Austin any warning of the strikes.
Iran has been bracing for reprisal by Israel all week. World leaders from the Middle East to the U.S. urged Prime Minister Benjamin Netanyahu to show restraint in the face of the Iranian attacks, but the Israeli leader and other top officials said the country would have little choice but to respond.
Iran's army chief, Maj. Gen. Abdolrahim Mousavi, said Wednesday that Iran would respond to any Israeli aggression, according to remarks carried by the IRNA state news agency.
Tehran has routinely accused Israel of attacks and sabotage activities targeting its nuclear and military sites in the past, including in Isfahan. Iran says its nuclear program is for peaceful purposes but Israel and allies accuse it of seeking to develop atomic weapons.
Any missile or drone strike on Iranian soil, no matter the target, would be a significant move for Israel. But it wouldn't necessarily be the first attack in Iran by Israel. Former Prime Minister Naftali Bennett said Israeli forces destroyed a drone base in Iran in 2022 under his orders.
In an interview with CNN on Thursday night, Iranian Foreign Minister Hossein Amirabdollahian warned against retaliation for the weekend assault. "In case the Israeli regime embarks on adventurism again and takes action against the interests of Iran, the next response from us will be immediate and at a maximum level," he said.
Information for this article was contributed by Arsalan Shahla, Peter Martin and Jennifer Jacobs of Bloomberg News (TNS); by Jon Gambrell and Nasser Karimi of The Associated Press; and by Farnaz Fassihi, Roman Bergman and Patrick Kingsley of The New York Times.