Israel is vowing to retaliate against Iran, risking further expanding the shadow war between the two foes into a direct conflict after an Iranian attack over the weekend sent hundreds of drones and missiles toward Israel.

Israeli officials have not said how or when they might strike. But as countries around the world urge Israel to show restraint and the threat of a multi-front war mounts, it’s clear that a direct Israeli attack on Iranian soil would lead to major fallout.

Iran says it carried out the strike to avenge an Israeli airstrike that killed two Iranian generals in Syria on April 1. It has pledged a much tougher response to any Israeli counterattack attack on its soil.

World leaders urge restraint as Israel says it will respond to Iran’s attack

With Israel focused on its war against Hamas in Gaza, and already battling Iranian-backed Hezbollah militants in Lebanon every day, the U.S. has urged Israel to show restraint.

U.S. officials say President Joe Biden has told Israeli Prime Minister Benjamin Netanyahu that the U.S. will not participate in any offensive action against Iran, and the president made “very clear” to Netanyahu “that we do have to think carefully and strategically” about the risks of escalation.

Israel’s war cabinet has spent the last two days debating their next move. Here are some considerations key to their decision.

INCREASING ISRAELI ISOLATION
Israel’s successful air defense Saturday night — conducted in tandem with the U.S., Britain, France and Jordan — bought the country a brief moment of international support and sympathy after months of mounting international isolation over the Gaza war. The six-month offensive has killed nearly 34,000 Palestinians, according to local health officials, and unleashed a humanitarian catastrophe.

A coalition of international partners helped Israel defend itself effectively. Israel’s military says 99% of the weapons were intercepted, with few reaching Israeli airspace. The attack caused only minor damage and wounded one person: a 7-year-old girl.

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This coalition worked under the leadership of the U.S. Central Command, which oversees American forces in the region. It works closely with Israel and moderate Arab countries to form a unified front against Iran.

Jordan, a country whose population is predominantly pro-Palestinian, joined the effort, despite being at odds with Israel over the war in Gaza, calling its participation self-defense.

It also appears likely that help may have come from regional powerhouse Saudi Arabia, which does not have official relations with Israel. A map released by Israel shows many of the Iranian missiles flying through Saudi airspace.

Israel has been careful not to identify its Arab partners, but an Israeli air force official, speaking on condition of anonymity to discuss the mission, said Israeli warplanes needed to fly “east of Israel” to shoot down missiles.

Yoel Guzansky, a senior researcher at the Institute for National Security Studies, a Tel Aviv think tank, said Israel would be risking this goodwill if it acts alone.

“Israel can take advantage of this and buy itself a lot of credit right now, if it does not launch a massive retaliatory attack," he said. "But if it does attack, a lot of credit is lost.”

The tacit support of Arab states does not mean they would assist Israel in a counterattack on Iran. Any air or missile response other than ballistic missiles — which would arc over neighboring countries’ airspace rather than through it — would require overflights of surrounding countries, which technically would require Israel obtain permission from those Arab neighbors, said Daniel Byman, a senior fellow with the Washington-based Center for Strategic and International Studies.

“With Saudi Arabia and Jordan, there’s kind of a route and access questions,” in terms of whether they would grant Israel overflight clearance.

“From Iran’s point of view, that would be seen as a hostile act,” Byman said. “And even though these countries don’t like Iran, they’re not terribly eager to be seen on the side of Israel doing that.”

FEARS OF A MULTI-FRONT WAR
A major retaliatory strike on Iranian soil risks sparking a full-scale regional war, so any response must be carefully calculated.

A direct strike on Iranian soil would almost certainly result in a brutal counterattack and risk prompting Hezbollah to launch further attacks. The Iranian-backed Lebanese group has a far more powerful arsenal than Hamas, but has so far shown hesitancy about engaging in an all-out war.

Some 60,000 citizens in northern Israel already have been forced to evacuate their homes due to ongoing exchanges with Hezbollah. Heavier fighting would likely force them to spend even more time away from home.

A direct conflict would also further stretch Israel's military, remove its focus from Gaza and hamper Israel’s war-wearied economy.

Any major attack on Iranian soil could also undermine shaky U.S. support for the war.

Two U.S. officials said Israel has not yet told the U.S. how it intends to respond. But the officials, speaking on condition of anonymity to describe diplomatic discussions, said Israel has signaled that whatever it does will be designed to prevent a worsening of the already tense regional security situation. That could point to a more limited action, such as a strike on Iranian proxies across the region or a cyber attack on Iran.

Tamar Hermann, a polling expert at the Israel Democracy Institute, says most Israelis are in favor of some sort of military response as long as it is coordinated with regional allies, including the United States.

“If it is done with no consultation and no agreement with allies … support will be much smaller,” Hermann said.

MILITARY CAPACITY
Israel’s army is vastly superior to others in the region. It possesses a range of high-tech weaponry, including F35 fighter planes that can launch long-range munitions. Experts say it has the ability to directly strike Iran or its proxies in the region.

Fabian Hinz, a weapons expert and research fellow at the International Institute for Strategic Studies, said the Iranian air force is “not even remotely comparable.” He said the force is composed of a collection of planes from the 1980s and 90s, with some dating back to the reign of the Shah Mohammad Reza Pahlavi who ruled the country until 1979.

The extent of the Islamic republic’s air defense system is less known, he said. Many of Iran’s missile sites and nuclear installations are deep underground, making them difficult to hit, Hindz added. Israel might also need the agreement of Gulf Arab countries to use their airspace — something that is not guaranteed.

“I don’t think it’s going to be a full-scale Israeli attack against many targets all over Iran," said Raz Zimmt, another senior researcher at Israel's INSS. "It will probably be limited against one or two, perhaps inside Iran.”