Israel, Iran seek deterrence but risk escalation

Iran, after launching a massive missile-and-drone attack on Israel over the weekend, is threatening to strike again if Israel retaliates. Lebanese militia Hezbollah fires at Israeli forces almost every day despite frequent poundings by Israel. And Hamas continues to launch rockets at Israel even after being bludgeoned following its Oct. 7 attack, which killed 1,200 people, according to Israeli officials.

With no side willing to compromise for fear of showing weakness and all players seeking greater deterrence, the risk of stumbling into a regional war increases.

“If they continue to exchange blows, it’s a slippery slope to a real escalation," said Ofer Fridman, a former Israeli officer and scholar of war studies at King’s College London.

Deterrence—the principle that any attack will be met by a far more punishing response—is the foundation of defense for most countries. It has been one of three pillars of Israel’s strategic culture for decades, Fridman said.

If deterrence fails, then Israel relies on early warning of any attack. If both fail, then Israel seeks to rapidly inflict a crushing, even humiliating defeat on the battlefield so that deterrence is restored and the adversary doesn’t dare strike at Israel again—at least for many years.

Before Iran’s attack, Israel threatened a major retaliation if Tehran struck. After Iran launched drones but before its more dangerous ballistic missiles took off, Israeli Prime Minister Benjamin Netanyahu said in a video statement, “Whoever harms us, we will harm them."

Iran is now using similar terms about potential Israeli retaliation. “The smallest action against Iran’s interests will definitely be met with a severe, extensive and painful response against all its perpetrators," said Iranian President Ebrahim Raisi.

Iran’s drone-and-missile attack on Israel departed from a yearslong regional military strategy, in which it built up a network of proxy militia groups that have allowed it to strike militarily stronger adversaries, particularly the U.S. and Israel, while minimizing the risk of attacks on Iranian soil.

“We have decided to create a new equation," said the head of Iran’s Islamic Revolutionary Guard Corps, Maj. Gen. Hossein Salami, on Sunday, adding that any strike on Iran’s interests in the region would be met with direct attacks from Iran.

The attack has now raised the risk of an Israeli response and further cycles of violence between the two countries, military analysts said.

“Iran’s moves are very calculated and choreographed. But at the same time, they’re not risk-free," said Hamdi Malik, an associate fellow with the Washington Institute for Near East Policy and an expert on Iran’s militia network. “Iran is willing to take some calculated risk."

Israel’s deterrence failure became painfully clear on Oct. 7, when it was stunned by an invasion of thousands of militants from Gaza.

Until that morning, the prevailing assessment across Israel’s security and political echelons was that Hamas wasn’t interested in battling with Israel. Netanyahu and security chiefs said Hamas had taken a forceful blow in a 2021 fight and was deterred.

Israel, confident it had defanged Hamas, switched to a policy in which it slowly increased work permits for Gazans. Israel hoped its economic leverage would deter Hamas from further conflict. What Netanyahu and his advisers failed to appreciate was that economics didn’t sway Hamas.

“The basic problem here is we face ideological players," said Michael Milshtein, a former Israeli intelligence officer for Palestinian affairs.

Hamas is different from Israel’s other enemies, he said, because conventional deterrence doesn’t work with the movement. It is too committed to its goal of defeating Israel, has nurtured a culture of sacrifice for the cause, and has no real space for internal dissent, he added.

“It’s a zero-sum game," Milshtein said, meaning that either Hamas is fully defeated or will remain a threat. “When you confront such players, you can temporarily buy a calm situation or a more-quiet period, but at the end of the day they have ideological goals and you have no way to escape."

Fridman said Israel needed to pivot from the idea that it can perpetually deter its enemies.

“Since the establishment of Israel, it’s been moving from one conflict to another, assuming if we beat them hard enough they will stop attacking us," Fridman said. “It doesn’t work. We need to find a political solution."

Washington is now advocating a change in Israel’s approach, which could slow escalation. The Biden administration is effectively telling Israel to be satisfied with the security offered by early warning of Iran’s attack, bolstered by cooperation with the U.S., European allies and some Arab countries, and not retaliate.

In Israel, however, there is a strong desire to restore deterrence, not just rely on sharp eyes and a big shield. “Iran crossed a red line," said Danny Danon, a senior lawmaker from Netanyahu’s Likud party. “I think now the dilemma is how to respond in a way that will not escalate the situation."

Jared Malsin and Marcus Walker contributed to this article.

Write to Dov Lieber at dov.lieber@wsj.com