Why did Iran attack Israel? Here's a look at what happened and what could come next

Iran launched at least 180 missiles into Israel on Tuesday, the latest in a series of rapidly escalating attacks between Israel and Iran and its Arab allies.

The attack set off air raid sirens across the country and sent residents scrambling for shelter.

But what exactly happened and what do the attacks have to do with the yearlong war between Israel and Hamas in Gaza?

The latest attack, which comes just before the start of the Jewish High Holy Days, threatens to push the Middle East closer to a regionwide war.

Israel has vowed to retaliate against Iran.

At the heart of the recent escalation is the war in Gaza. On Oct. 7 Hamas terrorists attacked southern Israel, where militants killed some 1,200 people, mostly civilians, and took another 250 hostage.

Here's what to know:

Why did Iran launch missiles toward Israel?

Iran's decision came after its militant allies, known as the Axis of Resistance, suffered a series of major blows in recent weeks.

Iran said the missile attack was in response to the targeted killing of Hezbollah's top leader, Hassan Nasrallah, along with an Iranian general killed alongside him and Ismail Haniyeh, the political leader of Hamas who was killed in an explosion in Tehran in July that was widely blamed on Israel.

Israeli airstrikes killed Nasrallah, Hezbollah's top leader, and several of his top commanders in quick succession, indicating that Israeli intelligence has thoroughly penetrated the group. Israel has also bombed what it says are militant targets across large parts of Lebanon, killing over 1,000 people, a quarter of whom are women and children, according to Lebanon's Health Ministry.

Last month, thousands of explosives hidden in pagers and walkie-talkies used by Hezbollah detonated, killing dozens of people and maiming thousands, including many civilians. Israel is widely believed to be behind the attack.

Iran may have felt it had to respond to avoid being seen as hanging its allies out to dry. It also appears to be trying to reestablish deterrence after the unspoken rules of its long-running shadow war with Israel have crumbled.

What kind of missiles did Iran use in the attack?

Iran's ballistic missile attack on Israel caused few casualties and little damage as Israel largely deterred the missiles with its Iron Dome missile defense system, along with help from nearby U.S. naval destroyers.

Iranian state media said several types of ballistic missiles were used in the attack, including the Emad and Ghadr, as well as Iran’s new Fattah missile.

Officials last year claimed the Fattah, or “Conqueror” in Farsi, traveled as fast as 15 times the speed of sound with a range of up to 870 miles.

Missile experts who analyzed footage of remains of missiles recovered after the attack suggested the Fattah had been used. Questions remain over how maneuverable the missile is as it comes back into the atmosphere. The more irregular the missile’s flight path, the more difficult it becomes to intercept.

The Israeli Defense Force said it intercepted many of the incoming Iranian missiles using its multitiered air defense system, though some landed in central and southern Israel and two people were lightly wounded by shrapnel. One of the missiles killed a Palestinian worker from Gaza who was stranded in the Israeli-occupied West Bank since the start of the war.

How is Israel likely to respond?

Israel has a range of options in responding to the attack, spanning from a largely symbolic strike to a broader air campaign targeting Iran's infrastructure or even its controversial nuclear program.

Yoav Limor, a military correspondent for the Israel Today newspaper, said the failure of the Iranian attack to cause major casualties or damage gives Israel time to consider its response.

“Israel can stick to the eye-for-an-eye equation (as it did in April) and only hit military targets," he wrote.

"It can also attack infrastructure targets that will hurt the Iranian regime and the Iranian economy, such as oil, gas and petrochemical facilities, in the hope that the ensuing crisis in Iran will also provoke public anger against the regime.”

Israel's response may depend on how far the United States is willing to escalate and whether American forces will take part.

What is the latest on Israel's operations in Lebanon?

Hezbollah, designated a terrorist organization by the U.S. government, has fired hundreds of rockets, missiles and drones into Israel since last October, when it began attacking Israel in support of its Hamas allies in Gaza.

The sides have continued to trade strikes in recent days, with Israeli warplanes hitting Beirut and artillery firing at targets along the border.

Hezbollah said Wednesday that its fighters clashed with Israeli troops near the border. That would mark the first ground combat since the start of the incursion.

The Israeli military said ground forces backed by airstrikes had killed militants in “close-range engagements” without saying where.

Israel said Tuesday that it had launched limited ground incursions into Lebanon to locate and destroy Hezbollah infrastructure, but there are signs that a wider offensive is planned.

Throughout Monday, the Israeli military sent warnings to residents to immediately evacuate in anticipation of the strikes and to stay away from places where Hezbollah stores weapons — something many would have no way of knowing.

Israel has moved thousands of troops, tanks and artillery to the border in recent days, and it has warned residents to evacuate around 50 villages and towns in a U.N.-declared buffer zone in southern Lebanon, telling them to relocate to more than 37 miles north of the border.

What is Hezbollah?

Hezbollah, a Lebanese militant group and political party backed by Iran, Israel’s chief regional rival, rose to regional prominence after fighting a devastating monthlong war with Israel in 2006 that ended in a draw.

Whereas Hamas rules Gaza, Hezbollah is a powerful militia with enormous influence inside Lebanon, and has representatives in the country's parliament and government.

Hezbollah and Hamas are allies that consider themselves part of an Iran-backed “Axis of Resistance” against Israel.

Hezbollah began firing rockets, missiles and drones into northern Israel after Hamas' Oct. 7 attack out of Gaza triggered the war there.

What happened in Gaza?

Hamas' Oct. 7 terrorist attack in southern Israel killed some 1,200 people, mostly civilians, and took another 250 hostage. Some 100 have not yet been released, around 65 of whom are believed to be alive.

The war continued through the following months, now approaching nearly a year since the Hamas' deadly attack.

Israel has continued to strike what it says are militant targets in Gaza even as attention has shifted to Lebanon and Iran.

Israel's retaliatory offensive has killed over 41,000 Palestinians, according to the Gaza Health Ministry. They do not say how many were fighters but say women and children make up more than half of the fatalities.

Diplomatic efforts have stalled and there is no end to the war in sight.

What is the difference between Lebanon and Gaza?

There are key differences between Gaza and Lebanon and how Israel has so far conducted its operations.

While Israel’s actions in Lebanon may have echoes of Gaza, the conflicts are different. In Gaza, Israel’s goal is the complete destruction of Hamas, whereas Israel’s stated goal in Lebanon is to push Hezbollah away from its border.

Israel and Hezbollah last had a direct war in 2006, which lasted 34 days and killed over 1,500 people between Lebanese civilians and Hezbollah fighters. Since then, Israel and Hezbollah have been in a shadow war – but not with the same kind of intensity and daily pattern that we have seen in the post-Oct. 7 landscape.

Unlike Gaza, Lebanon is also a mixed tapestry of political and religious groups, including Christian and Sunni-majority areas where there is significant opposition to the Iran-backed Shiite Hezbollah.

U.N. Secretary General Antonio Guterres, speaking at the United Nations Wednesday, said the world “cannot afford Lebanon to become another Gaza.”

With Gaza's borders in Egypt and Israel sealed, residents of the crammed territory are trapped with nowhere to go, whereas in Lebanon, those fleeing Israeli strikes have been able to move to safer areas. Thousands have fled to neighboring Syria, while others have left through the country’s airport.

What does the U.S. say?

The Biden administration likely wants to send a message that will shore up American deterrence. But it might also be wary of an all-out war that could draw in American forces stationed in the region and Arab allies, and which could send oil prices soaring weeks before the U.S. presidential election.

White House National Security Adviser Jake Sullivan called Iran’s attack a “significant escalation,” and President Joe Biden said he’s in “active discussion” with aides about what the appropriate response should be.

United States Secretary of Defense Lloyd Austin told Israel’s defense minister that he agreed on the need for a ground offensive inside Lebanon to rid the border area of Hezbollah weapons and other means it can use to carry out attacks across the frontier.

Austin told Yoav Gallant in a call that the U.S. supports Israel’s right to defend itself and discussed Israel’s military operations.

“We agreed on the necessity of dismantling attack infrastructure along the border,” Austin said in a statement posted on the X social platform.

The White House National Security Council said Israel’s “limited operations” to destroy Hezbollah infrastructure across the border were in line with the country’s right to defend itself.

The NSC, however, warned that the an expansion of that operation was a risk. It added that a diplomatic solution was the only way to achieve lasting stability along Israel’s border with Lebanon.

"This is in line with Israel’s right to defend its citizens and safely return civilians to their homes. We support Israel’s right to defend itself against Hezbollah and all Iranian-backed terror groups. Of course, we know that mission creep can be a risk and we will keep discussing that with the Israelis,” the NSC said.