Azadeh Moshiri
Presenter, BBC News Channel

The international community has been on edge, waiting to see how Israel would respond, in a region where the word “escalation” has been used far more times than world leaders would be comfortable with.

US President Joe Biden has made it very clear he does not support Israel targeting either Iran’s nuclear research facilities nor its oil installations.

Right now, Iranian state media is playing down the attack, as it usually does.

The main questions at this stage are:

• how much damage has truly been inflicted
• will Iran feel the need to respond, at a time when its proxies are weakened and it's suffered a series of humiliations this year

Those humiliations include the killing of Ismail Haniyeh, the Hamas political chief, on Iranian soil, and the assassination of Hassan Nasrallah, the leader of Hezbollah.

Will this be yet another moment that leads to that dreaded slippery slope in the region?

• Watch Azadeh reporting on this story live by pressing watch live above

Sebastian Usher
Middle East regional editor

This attack has been anticipated since Iran launched nearly 200 ballistic missiles on Israel almost a month ago.

In a statement announcing that the operation was under way, the Israeli military spokesman said Israel had the "right and duty" to respond and that its defensive and offensive capabilities were fully mobilised.

Iranian state media has confirmed that explosions have been heard in the west of Tehran.

A news agency close to the Revolutionary Guards says that some military bases in the west and south west of the Iranian capital have been targeted.

The extent of the attacks and the precise targets are not yet clear.

The Syrian state news agency says that Israeli air strikes have also targeted some military sites in central and southern areas of Syria.

The office of the Israeli Prime Minister Benjamin Netanyahu has released a picture of him in the operations centre of the military headquarters during the attack.

As a reminder, you can stay up to date with the latest news from Israel, Iran and the rest of the Middle East region, along with analysis from experts, by clicking watch live at the top of this page.

The US President Joe Biden "has been briefed and is closely following the developments", according to our US news partner CBS.

We're still waiting for more information about what sites in Iran have been struck. So far, Israel has only said it is conducting strikes on "military targets."

Iran state TV says operations are continuing as "normal" at Tehran's two airports, according to the AFP news agency.

The White House says it understands that Israel is conducting the strikes in Iran as an "exercise of self-defence".

"We understand that Israel is conducting targeted strikes against military targets in Iran as an exercise of self-defence and in response to Iran’s ballistic missile attack against Israel on October 1," a National Security Council spokesman tells the BBC's US news partner CBS.

Iranian intelligence officials told state TV that the sound of loud explosions "could be from the activation from Iran's air defence system", according to the Reuters news agency, citing state TV.

Watch Israel Defense Forces (IDF) spokesman Daniel Hagari read out a statement announcing the strikes against Iran in a video, which you can watch below.

Israel's military says that, "like every other sovereign country in the world, the State of Israel has the right and the duty to respond", due to "the regime in Iran and its proxies in the region... relentlessly attacking Israel" since 7 October 2023.

"Our defensive and offensive capabilities are fully mobilized," the military says.

"We will do whatever necessary to defend the State of Israel and the people of Israel," it adds.

Israel's military says it is conducting "precise strikes on military targets in Iran".

We're getting reports of multiple explosions heard in the Iranian capital, according to the country's state media.

Stick with us for updates on this breaking story.