Israel vowed to retaliate after Iran launched a ballistic missile attack on Israel on October 1. In that attack, Iran fired more than 180 missiles at Israel. Most were intercepted by Israel’s air defenses and US-led allied forces. Some hit air bases and other sites. A Palestinian was killed by a falling rocket casing.

Israel said it would retaliate, but did not say when or how. Since then there has been constant speculation about the timing of an Israeli attack and what form it might take – from limited strikes to massive attacks on Iran’s oil fields and nuclear sites.

The attack took place in the early hours of Saturday and appears to have been limited to missile production and launch sites and what Israel called “other aerial capabilities,” without being specific.

Why did Iran previously attack Israel and what was Israel’s response?

Iran said it attacked Israel on Oct. 1 in retaliation for the killing of the leaders of Hezbollah and Hamas – Iran-backed armed groups fighting Israel – and a senior Iranian commander.

Hezbollah leader Hassan Nasrallah and Brigadier General Abbas Nilforoushan were killed when Israel bombed the building they were in in the Lebanese capital, Beirut, on September 27. Hamas political chief Ismail Haniyeh was killed in an explosion at the compound where he was visiting Tehran on July 31. Iran blamed Israel for the attack, although Israel neither confirmed nor denied involvement.

Iran’s attack was the second direct attack against Israel. It came five months after it first attacked Israel with waves of around 300 drones and missiles. Israel said almost all had been intercepted. The attack was in response to an Israeli airstrike on an Iranian consular compound in the Syrian capital Damascus on April 1 that killed 13 people, including seven members of Iran’s overseas Quds Force. Two of those killed were a senior Quds Force commander and his deputy. Iran said the attack was a violation of its sovereignty.

The Quds Force is part of Iran’s most powerful armed force, the Islamic Revolutionary Guard Corps (IRGC).

The IRGC transports weapons and equipment, including high-precision missiles, through Syria to Hezbollah.

Israel retaliated for Iran’s attack with missiles and drones nearly three weeks later, attacking targets in Iran’s central Isfahan region. US officials confirmed the Israeli attack, although Israel did not comment. Israeli drones are said to have hit the radar for Iran’s Russian-made S-300 air defense missile system, which Israel believes would pose a particularly dangerous threat to any of its fighter jets in nearby airspace.

The attack on the radar was considered limited and designed to signal Israel’s ability to strike Iranian military assets.

Why are Israel and Iran enemies?

Before Iran’s direct attack on Israel on April 1, Iran and Israel had been engaged in a shadow war for years – attacking each other’s assets without admitting responsibility.

These attacks have intensified considerably during the Gaza war, which was triggered by the attack by the Palestinian group Hamas on nearby Israeli communities last October.

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

Iran does not recognize Israel’s right to exist and seeks its eradication. The country’s supreme leader, Ayatollah Ali Khamenei, called Israel a “cancerous tumor” that “will undoubtedly be uprooted and destroyed.”

Israel views Iran as an existential threat, as evidenced by Tehran’s rhetoric, its buildup of proxy forces in the region, including the Lebanese Shiite militant group Hezbollah, which has vowed to destroy Israel, and its funding and arming of Palestinian groups, including Hamas.

It also accuses Iran of secretly trying to develop nuclear weapons, although Iran denies that it has tried to build a nuclear bomb.

What are the military capabilities of Israel and Iran?

Iran is much larger than Israel geographically and has a population of nearly 90 million, almost ten times the size of Israel – 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 provided significant sums to its proxies – Yemen’s Houthis and Lebanon’s Hezbollah.

What it lacks are modern air defense systems and fighter jets. Russia is believed to be cooperating with Iran to improve them, including by providing Su-35 fighter jets in exchange for the military support Tehran has given Moscow in its war against Ukraine.

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

Israel also has experience conducting strikes deep inside hostile territory. The shortest distance between Iran and Israel is about 1,000 km (620 miles).

Israel is alleged to have nuclear weapons, but maintains an official policy of ambiguity. Iran does not have nuclear weapons, although Western states suspect it is secretly seeking to develop them. Iran strongly denies that it is trying or even wants to obtain nuclear weapons.

Like Israel, Iran has a civilian nuclear program, although it has been suspected for decades of secretly running a parallel program to make the material – enriched uranium – for nuclear bombs and the missiles to deliver them.

In May, the head of the global nuclear watchdog said Iran was “weeks, rather than months” away from having enough material for a nuclear bomb. That doesn’t mean Iran is weeks away from a bomb, however. It would require a final step of enriching that material to military grade and having warheads, which they are not believed to possess.

Israel is not a signatory to the Nuclear Non-Proliferation Treaty (NPT), although Iran is. The NPT aims to stop the spread of nuclear weapons and requires members to open their nuclear facilities to inspection to verify that they are being used for purely peaceful purposes.

A 2015 UN-backed deal with Iran, under which it agreed to curbs on its nuclear activities in exchange for the lifting of economic sanctions, largely collapsed after then-President Trump withdrew the US in 2018. Iran intensified nuclear program since then.

Who are Iran’s allies?

Iran has built a network of allies and proxy forces in the Middle East that it says are part of an “axis of resistance” that challenges 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.

Iran’s relationship with Russia is also becoming increasingly significant. In December, Russia’s foreign ministry said the countries would speed up work on a “major new interstate agreement.”

Iran has supplied Russia with Shahed attack drones. In February, Reuters cited sources as saying Iran had also supplied ballistic missiles. Iran denied the report. Meanwhile, Iran says Russia plans to supply Iran with more advanced aircraft.