There are at least two ways for mutual deterrence between states—also known as mutually assured destruction—to come to an end. As the Cold War taught us, one side in the conflict can simply collapse. But deterrence can also break down when one party decides to upend the equilibrium. For more than nine months after Hamas’s horrific October 7 attack on southern Israel and the start of Israel’s devastating onslaught in Gaza, hostilities between Israel and the Iran-led “axis of resistance” (the alliance that also includes Hezbollah, Syria, Iraqi paramilitary groups, and Ansar Allah—commonly known as the Houthis—in Yemen) built steadily. The fighting between Israel and Hezbollah in particular defied both sides’ previous red lines. Yet they appeared to steer clear of provoking all-out war.
Then, in late July, Israel attacked a residential guesthouse in Tehran, killing Ismail Haniyeh, the political leader of Hamas. Just hours earlier he had attended the inauguration of Iran’s new president, Masoud Pezeshkian. For Israel to assassinate Haniyeh while he was staying in the Iranian capital as an official state guest was deeply humiliating. Until then Iran’s leaders had tried to keep their enemy in a vise, using neither too little aggression nor too much. Now, however, if they wanted to restore deterrence, they must have felt they had no choice but to reply with a major show of force.
And yet they didn’t, at least not right away. President Pezeshkian has told journalists that the Biden administration asked them to hold off, on the grounds that Israel and Hamas (with help from Qatari and Egyptian mediators) were close to reaching a cease-fire in Gaza—which the axis required for deescalating its post–October 7 standoff with Israel. But no cease-fire materialized in the days that followed, and Israel, perhaps emboldened by Iran’s nonresponse, pressed its advantage. It was another illustration of US diplomatic bumbling in a year that has seen far too much of it. Last month, speaking at the UN General Assembly, Pezeshkian complained bitterly that the US had once again betrayed what little trust remained between the two powers.
Israel’s next surprise escalation came in September, when it set off explosives it had installed in Hezbollah fighters’ communications devices. It is unclear whether it planned the timing of the attack in advance or went ahead at the last minute under threat of imminent discovery. Either way, by creating disarray in Hezbollah’s ranks the pager attack allowed Israel to carry out massive strikes on southern Lebanon and Beirut, killing some two thousand people in a matter of days, many if not most of them civilians, and displacing more than a million. Israel also took the opportunity to decapitate the party’s senior command, killing a number of top commanders—and, most shocking of all, its leader, Hassan Nasrallah, who had enjoyed a status just below that of Iran’s own supreme leader, Ayatollah Ali Khamenei.
Hezbollah’s leaders seem to have thought that they possessed enough military strength—including a large enough rocket and missile arsenal—to hold their own in not just asymmetric but also conventional warfare against Israel. They also clearly underestimated how much intelligence Israel had gathered on them since 2006. (Indeed Israel devoted far more resources to Hezbollah than to Hamas, which it considered the lesser enemy.) In any case Hezbollah was not interested in sparking an all-out war—and it was clearly expecting that Israel, too, would prefer to maintain their mutual deterrence.
In fact Israel seems to want something quite different. Since October 7 the country has been determined to recover its shattered sense of security. Prime Minister Benjamin Netanyahu has been able to delay a domestic reckoning about the intelligence and security failures that occurred that day, but only for now. He may believe that he can only salvage his political career by dealing decisive blows not only to Hamas but also to Iran and its allies, especially Hezbollah, lest there be a reprise, sooner or later, of the dread day. He may also believe, as he has intimated in recent speeches, that he can effect regime change both in Lebanon and in Iran, thus removing one of Israel’s main threats—Iran’s nuclear program. The Biden administration may not be encouraging Netanyahu to proceed on that path, but he knows that the US will not let Israel down.
Netanyahu has long been hoping to establish a new Middle Eastern order erasing the Palestinian question. He proposed as much in a speech to the UN General Assembly a mere two weeks before October 7, when he brandished a map of Israel covering the entire territory between the Jordan river and the Mediterranean. When Hamas rolled the dice last October, it might have hoped to spark a regional war that would subvert those efforts. A year on, it may be getting its wish—but with the prospect of a positive outcome for Palestinians more remote than ever.
In the months leading up to October 7, Hamas was under growing pressure in Gaza. In 2006 it had won the Palestinian parliamentary elections, and the next year it began governing the territory, at which point Israel put the enclave under a long-term blockade. Through its control of Gaza’s borders and skies, Israel further restricted the population’s freedom of movement and its access to essential goods, creating what humanitarian workers called the world’s largest open-air prison. During these years Hamas fought Israel on several occasions, with the military support of Iran and Hezbollah. Meanwhile repeated Israeli bombardments made the Strip increasingly unlivable. Squeezed by the blockade, growing numbers of Gazans grew disaffected with a militant group that could not alleviate their suffering. In 2019 people started taking to the streets to protest worsening living conditions in what they called the “We Want to Live” movement. Hamas suppressed the demonstrations and arrested protesters.
Hamas is an awkward partner in the axis of resistance. The group’s ideology, grounded in both Sunni Islam and Palestinian resistance to Israel’s occupation, markedly differs from that of Iran and its other nonstate associates, which are confessionally Shia and have a political affinity with the leadership that emerged from the 1979 Islamic revolution. By forming the axis, Iran sent a clear message to the US and Israel: attack us and you risk a multifront war. As I argued earlier this year, Iran meant for its allies to harass their common enemies, serving as a kind of forward defense—not for them to pursue their domestic interests if doing so might harm its own strategic aims.
Hamas, however, had other ideas. Its leaders had long indicated that they were dissatisfied with governing under Israeli siege and that they would rather fight the occupation militarily. For years they had been deeply perturbed that the Palestinian predicament—and the pursuit of a just solution to the Israeli–Palestinian conflict—was fading from international awareness. They have also repeatedly invoked Israeli trespassing at Al-Aqsa and other Muslim holy sites in Jerusalem, where the religious and nationalist strands of the group’s ideology converge. They hoped, as their military commander Mohammed Deif suggested in a speech on October 7, that Iran and Hezbollah would join the attack that day, opening additional fronts.
That didn’t happen. By not notifying its patron and allies of its intentions, much less asking for Iran’s permission, the Hamas leadership in Gaza caught them off-guard. Iran had not intended to start this fight. Yet it risked making the alliance seem weak—especially to its own fighters and followers—by not responding at all.
What followed was a yearlong dance in which Iran and its allies attacked Israel enough to show their solidarity with Hamas and the Palestinians but not so much as to provoke Israel into launching an all-out regional assault. This helps explain the mutual vexation between Hamas and its axis partners. Iran has has at times seemed frustrated that Hamas did not notify it about the October attack in advance; Hamas leaders, in turn, have expressed disappointment at their allies’ half-hearted response.
On October 8, 2023, saying it was acting in solidarity with Palestinians, Hezbollah struck first, targeting Israeli positions in Shebaa Farms, a fourteen-square-mile territory on Lebanon’s border with Syria that Israel has occupied since 1967. Israel retaliated, and from that moment on the conflict escalated. Hezbollah rockets rained on northern Israel; Israel bombarded southern Lebanon. Tens of thousands of civilians were displaced from both sides of the border.
Iraqi groups joined the fray, taking potshots at US bases in Iraq and Syria, and meeting a forceful response. So did the Houthis: having had little success at reaching Israel with missiles, they targeted commercial vessels in the Red Sea they claimed had Israeli connections. The US and allied navies responded by bombing Houthi launching and storage sites inside Yemen, following which the Houthis attacked those navy ships as well. Eventually both the Iraqi groups and the Houthis directly attacked Israel—but far less successfully than Hezbollah.
None of these tit-for-tat attacks disturbed the overall balance of mutual deterrence. Since both sides appeared reluctant to escalate beyond a certain level, Israel was free to pursue its war against Hamas, which amounted to a collective punishment of Gaza, without significant restraint. The Israeli military has leveled the strip’s infrastructure and housing; killed over 42,000 people, with thousands more thought to be buried under the ruble; and displaced almost the entire population—70 percent of whom are refugees from the 1948 nakba or their descendants—to ever smaller “safe” areas that it has also attacked, invariably on the accusation that Hamas had bases in these civilian enclaves.
For the first few months Iran cheered the actions of its allies but otherwise stayed out of the fighting. Then, on April 1, Israel directly hit the Iranian consulate in Damascus, killing, among others, a senior commander of the Qods force, the expeditionary unit of the Islamic Revolutionary Guard Corps responsible for advancing Iran’s security interests in Arab countries. Two weeks later Iran launched a volley of some three hundred drones and cruise and ballistic missiles at Israel. It was an unprecedented display of military might, but it had little material impact. Tehran had used mostly lumbering munitions and telegraphed its intentions well ahead of time, allowing Israel and the US to prepare the defense.
In effect Iran was sending a calibrated message: we can hit you but don’t want to hit so hard that you feel compelled to counter-escalate. Israel’s retort—a single strike at Iranian military infrastructure located near nuclear facilities—was minimal enough to allow Iran to desist from retaliating. The pattern of mutual deterrence held, however tenuously, until Haniyeh arrived in Tehran in late July and Israel decided to assassinate him. It may have reckoned that it could exploit Iran’s resistance to fighting an all-out war; a similar calculation may have informed the decision to kill Nasrallah in September.
So far, that reasoning appears to have been validated. On October 1, in retaliation for the killings of Haniyeh, Nasrallah, and senior Hezbollah commanders, Iran attacked Israel again, this time firing a volley of some 180 mainly ballistic missiles. Because Israel and the US had less time to prepare, a number of the missiles penetrated Israel’s defenses, striking two airbases and a site close to the headquarters of its spy agency, the Mossad. But Israeli accounts suggest the damage was limited. There was one casualty: a Palestinian man in the occupied West Bank was hit by the debris of a missile that was successfully intercepted in the skies above.
By targeting military sites, Iran was still signaling restraint and a desire to end things there. Yet the spiral toward full-scale war may have its own inexorable logic. Escalation begets escalation when neither side can afford to stand down. The Iranian leadership had come under harsh criticism before October 1 for looking weak, both at home and from its nonstate allies in the region. The Israeli public, shocked by the October 1 barrage, stood fully behind its leaders when they vowed revenge and may not mince their words if their government exacts none.
The prospect of a wider war in the region is thus no longer far-fetched. If Israel attacks Iran again, depending on the scale and targets, the Iranian leadership may have little choice but to make an even more muscular response. Hezbollah may be down, but it is far from out: it still fires daily volleys of rockets into northern Israel. A multifront war—which the axis refers to as the “ring of fire” around Israel—could also engulf countries that so far have remained on the sidelines: Syria, Jordan, and perhaps even Turkey, Egypt, and the Gulf states.
What this means is that Netanyahu will be unlikely to reshape the region, at least the way he envisions it. In his UN speech in September 2023, he discussed opening a major trading corridor from India to Europe through the Gulf states, Jordan, and an Israel that extended from the river to the sea. That seems like a pipe dream now, as the region threatens to dissolve into chaos. And whatever changes Hamas may have hoped to set in motion on October 7, the Palestinians will certainly not benefit from the further violent disorder that looms.
It did not have to go this way. The US’s contribution to the present crisis, in particular, demands close scrutiny. After October 7 the Biden administration sent its diplomats into the region to keep things calm, while at the same time dispatching warships to deter Iran and Hezbollah from launching an all-out attack on Israel. That display of military power might, in turn, have emboldened Netanyahu, who repeatedly undermined US attempts to mediate a cease-fire in Gaza and most recently Lebanon. All along, perhaps worried about losing domestic support, Biden did not meaningfully pressure Netanyahu to settle for a diplomatic solution. Whoever wins next month’s elections, the region is turning into a hell from which the US will have trouble escaping.