Israel said it struck military sites in Iran early on Saturday in retaliation for Tehran's attacks on Israel earlier this month, the latest attack in the escalating conflict between the heavily armed rivals.
Iranian media reported multiple explosions over several hours in the capital and at nearby military bases, but there were no immediate reports of damage or casualties.
Before dawn, Israel's public broadcaster said three waves of strikes had been completed and that the operation was over.
The Middle East has been on edge awaiting Israel's retaliation for a ballistic-missile barrage carried out by Iran on October 1, in which around 200 missiles were fired at Israel and one person was killed in the West Bank.
Tensions between arch rivals Israel and Iran have escalated since Hamas, the Iran-backed Palestinian militant group based in Gaza, attacked Israel on October 7, 2023. Hamas has been supported by Lebanon-based Hezbollah militants, also backed by Iran.
Fears that Iran and the US would be drawn into a regional war have risen with Israel's intensifying assault on Hezbollah since last month, including airstrikes on the Lebanese capital Beirut and a ground operation, as well as its year-old conflict in the Gaza Strip.
"In response to months of continuous attacks from the regime in Iran against the State of Israel – right now the Israel Defense Forces is conducting precise strikes on military targets in Iran," Israel's military said in a statement.
The military said later that it had completed its "targeted" attacks against military targets in Iran, adding that its planes had safely returned home.
Israel has the right and duty to respond to attacks from Tehran and its proxies, which have included missile strikes launched from Iranian soil, the military said.
Targets did not include energy infrastructure or nuclear facilities, a US official said.
US President Joe Biden had warned that Washington, Israel's main backer and supplier of arms, would not support a strike on Tehran's nuclear sites and has said Israel should consider alternatives to attacking Iran's oil fields.
"Iran reserves the right to respond to any aggression, and there is no doubt that Israel will face a proportional reaction for any action it takes," the semi-official Tasnim news agency said on Saturday, quoting sources.
Iranian state TV quoted a military spokesman as saying the explosions heard in Tehran were linked "to air defense systems reacting to efforts by the Zionist regime (Israel) to attack three locations outside the city of Tehran."
Videos carried by Iranian media showed air defences continuously firing at apparently incoming projectiles in central Tehran, without saying which sites were coming under attack.
The semi-official Iranian Fars news agency said several military bases in the west and southwest of Tehran had also been targeted.
A spokesperson for Iran's Civil Aviation Organization said flights on all routes were cancelled until further notice, state news agency IRNA reported.
Neighbouring Iraq also suspended flights in all of its airports until further notice, its state news agency said.
Israel targeted some military sites in Syria's central and southern parts with airstrikes early on Saturday, Syrian state news agency SANA reported. Israel has not confirmed striking Syria.
Israel said Prime Minister Benjamin Netanyahu, Defense Minister Yoav Gallant and other security officials were closely following the operation at the military's command and control centre in Tel Aviv.
Gallant spoke to US Defense Secretary Lloyd Austin shortly after Israel's response began, a U.S. defence official said.
The United States was notified by Israel ahead of its strikes on targets in Iran but was not involved in the operation, another US official told Reuters.
US Secretary of State Antony Blinken, in the Middle East for another attempt to broker a peace deal, said on Wednesday Israel's retaliation should not lead to greater escalation.
Even as it sought to convince Israel to calibrate its strikes, the United States moved to reassure its closest ally in the Middle East that it would aid in its defence should Tehran decide to stage a counter-attack.
This included Biden's decision to move the U.S. military's THAAD anti-missile defences to Israel, along with about 100 U.S. soldiers to operate them.
