The risk of a wider conflagration between heavily armed Israel and Iran has convulsed a region already on fire with warfare in Gaza and Lebanon, but it was not clear whether the overnight strikes would trigger further escalation.
Israel's military said scores of jets had completed three waves of strikes before dawn against missile factories and other sites, and warned its heavily armed arch-foe not to hit back.
"I can now confirm that we have concluded the Israeli response to Iran's attacks against Israel. We conducted targeted and precise strikes on military targets in Iran — thwarting immediate threats to the State of Israel."— Israel Defense Forces (@IDF) Watch IDF Spokesperson RAdm. Daniel Hagari talk about the… pic.twitter.com/1OOss3etpVOctober 26, 2024
Iran said its air defences had successfully countered the attack but two soldiers were killed and some locations suffered "limited damage".
A semi-official Iranian news agency vowed a "proportional reaction" to the Israeli strikes.
Tensions between Iran and Israel have grown rapidly since the October 7, 2023, attack on Israel by Iran-backed Hamas.
Fears of an escalation have increased since October 1 when Iran launched about 200 ballistic missiles at Israel, killing one person in the Israeli-occupied West Bank, in response to earlier Israeli moves and prompting new vows of retaliation.
Escalating conflict in Lebanon, where Israel is waging an intense campaign against Iran's main regional ally Hezbollah to stop it from firing rockets into northern Israel, has raised the temperature further.
With the US and many Middle Eastern countries urging restraint, all eyes are on how Iran will respond to Saturday's strikes.
Iranian news sites showed footage of passengers at Tehran's Mehrabad Airport, seemingly meant to show there was little impact.
Local media had reported blasts over several hours in the capital and at nearby military bases.
Iran fired about 200 missiles at Israel on October 1, killing one person in the West Bank. (AP PHOTO)
Israel's military, signalling it did not expect an immediate Iranian response, said there was no change to public safety restrictions across the country.
Israel's military said it had struck truck missile manufacturing facilities and surface-to-air missile arrays, adding its planes had safely returned home.
"If the regime in Iran were to make the mistake of beginning a new round of escalation, we will be obligated to respond," the military said.
Targets did not include energy infrastructure or Iran's nuclear facilities, a US official said.
US President Joe Biden had warned Washington, Israel's main backer and supplier of arms, would not support a strike on Tehran's nuclear sites and said Israel should consider alternatives to attacking Iran's oil fields.
Iranian authorities have repeatedly warned Israel against any attack.
"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, citing sources.
A senior Biden official said Israel's "targeted and proportional strikes" should be the end of direct exchange of fire between the two countries but the US was fully prepared to defend Israel if Iran responded.
Israel says it has the right and duty to respond to attacks from Tehran and its proxies. (AP PHOTO)
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.
Tasnim news agency said Islamic Revolutionary Guard Corps bases that were attacked were not damaged.
Israel targeted some military sites in Syria's central and southern parts with air strikes early on Saturday, Syrian state news agency SANA reported.
Israel has not confirmed striking Syria.
Israel said Prime Minister Benjamin Netanyahu, Defence Minister Yoav Gallant and other security officials had closely followed the operation at the military's command and control centre in Tel Aviv.
Israel notified the US before its strikes, but Washington was not involved in the operation, a US official told Reuters.
Efforts to secure a ceasefire and hostage-release deal in Gaza, which could help cool the wider conflict, are expected to resume in Doha when negotiators fly there on Sunday.
Months of talks have made little progress.
