Why has Iran attacked Israel?

By Raffi Berg, Tom Spender and Jonathan Beale, defence correspondent, BBC News

Iran launched drones and missiles towards Israel after vowing retaliation for a deadly strike on its consulate in the Syrian capital Damascus.

Israel has not said it carried out the consulate strike, but is widely believed to have been behind it.

It is the first time that Iran has attacked Israel directly.

Previously Israel and Iran had been engaged in a years-long shadow war - attacking each other's assets without admitting responsibility.

Those attacks have ratcheted up considerably during the current war in Gaza sparked by the Palestinian group Hamas's assault on nearby Israeli communities last October.

Why are Israel and Iran enemies?

The two countries were allies until the 1979 Islamic revolution in Iran, which brought in a regime that has used opposing Israel as a key part of its ideology.

Iran does not recognise Israel's right to exist and seeks its eradication.

The country's supreme leader, Ayatollah Ali Khamenei, has previously called Israel a "cancerous tumour" that "will undoubtedly be uprooted and destroyed".

Israel believes that Iran poses an existential threat as evidenced by Tehran's rhetoric, its build-up of proxy forces sworn to Israel's destruction, its funding and arming of Palestinian groups including Hamas and of the Lebanese Shia militant group Hezbollah, and what it believes is Iran's secret pursuit of nuclear weapons, though Iran denies seeking to build a nuclear bomb.

Iran wanted to hit back after attack on consulate

Iran says Saturday night's bombardment of Israel is a response to the 1 April air strike on an Iranian consulate building in the Syrian capital Damascus, which killed senior Iranian commanders.

Iran blames Israel for the air strike, which it saw as a violation of its sovereignty. Israel has not said it carried it out but is widely assumed to have done so.

Thirteen people were killed, including Brig Gen Mohammad Reza Zahedi - a senior commander in the Quds force, the overseas branch of Iran's elite Republican Guards (IRGC). He had been a key figure in the Iranian operation to arm the Lebanese Shia armed group Hezbollah.

The consulate attack follows a pattern of air strikes against Iranian targets widely attributed to Israel. Several senior IRGC commanders have been killed in air strikes in Syria in recent months.

The IRGC channels arms and equipment, including high precision missiles, through Syria to Hezbollah. Israel is trying to stop these deliveries, as well as seeking to prevent Iran from strengthening its military presence in Syria.

Who are Iran's allies?

Iran has built up a network of allies and proxy forces in the Middle East that it says form part of an "axis of resistance" challenging US and Israeli interests in the region. It supports them to varying degrees.

Syria is Iran's most important ally. Iran, along with Russia, helped the Syrian government of Bashar al-Assad survive the country's decade-long civil war.

Hezbollah in Lebanon is the most powerful of the armed groups Iran backs. It has been trading cross-border fire with Israel on an almost daily basis since war erupted between Israel and Hamas. Tens of thousands of civilians on both sides of the border have been forced to leave their homes.

Iran backs several Shia militia in Iraq which have attacked US bases in Iraq, Syria and Jordan with rocket fire. The US retaliated after three of its soldiers were killed at a military outpost in Jordan.

In Yemen, Iran provides support to the Houthi movement, which controls the most populated areas of the country. To show support for Hamas in Gaza, the Houthis have fired missiles and drones at Israel and have also been attacking commercial shipping near its shores, sinking at least one vessel. The US and UK have struck Houthi targets in response.

Iran also provides weapons and training to Palestinian armed groups including Hamas, which attacked Israel on 7 October last year, sparking the current war in Gaza and the confrontations drawing in Iran, its proxies and Israel's allies in the wider Middle East. However, Iran denies any role in the 7 October attack itself.

How do Iran and Israel's military capabilities compare?

Iran is much bigger than Israel geographically and has a population of nearly 90 million, nearly ten times as big as Israel's - but this does not translate into greater military power.

Iran has invested heavily in missiles and drones. It has a vast arsenal of its own, but has also been supplying significant amounts to its proxies - the Houthis in Yemen and Hezbollah in Lebanon.

What it lacks is modern air defence systems and fighter jets. Russia is believed to be co-operating with Iran to improve those in return for the military support Tehran has given Moscow in its war with Ukraine - Iran has provided Shahed attack drones and Russia is reportedly now seeking to manufacture the weapons itself.

By contrast, Israel has one of the most advanced air forces in the world. According to the IISS military balance report, Israel has at least 14 squadrons of jets - including F-15s, F-16s and the latest F-35 stealth jet.

Israel also has experience of conducting strikes deep inside hostile territory.

Do Iran and Israel have nuclear weapons?

Israel is assumed to have its own nuclear weapons but maintains an official policy of deliberate ambiguity.

Iran does not have nuclear weapons and also denies it is attempting to use its civilian nuclear programme to become a nuclear armed state.

Last year the global nuclear watchdog found uranium particles enriched to 83.7% purity - very close to weapons grade - at Iran's underground Fordo site. Iran said "unintended fluctuations" in enrichment levels may have occurred.

Iran has been openly enriching uranium to 60 percent purity for more than two years in breach of a 2015 nuclear deal with world powers.

However that deal has been close to collapse since US President Donald Trump pulled out unilaterally and reinstated crippling sanctions on Iran in 2018. Israel had opposed the nuclear deal in the first place.

What message is Iran sending through its attack?

"We blocked. We intercepted. Together we will win," was how Israeli Prime Minister Benjamin Netanyahu assessed things.

But Tom Fletcher, a foreign policy advisor to several UK prime ministers and a former UK ambassador to Lebanon, said the Iranian salvo was a "chilling signal of Iran's capability and reach".

Leaderships in both Iran and Israel were both "under pressure at home, facing international criticism and are clearly ready to play with fire", he warned.

But he told the BBC that Iran's unprecedented attack appeared to have been carefully calibrated.

"Iran did telegraph these attacks in advance which made them easier to deter," he said, comparing it to exchanges of fire he had seen while ambassador to Lebanon where "the intent is to show the capability but not necessarily to escalate".

He also said it was "positive" that Iran chose to respond directly rather than through Hezbollah. Some Israelis have called for the military to expand its confrontation with the Lebanese armed group to push it back from the border.

Sanam Vakil from the Chatham House think tank said the attack had been a success from Iran's point of view and Tehran was "calling Israel's bluff".

"This is the first time that Iran has directly breached and violated Israel's sovereignty," she told the BBC.

"The strikes were certainly calibrated, directed to military installations with the aim of not inflicting too much damage or hurting anyone."

- This story was first published on the BBC