Iran’s ballistic missile strikes on Israel on October 1 have raised fears of an all-out war in the Middle East. The deepening spiral of bloodshed began on September 17 and 18 with the detonation across Lebanon of thousands of pagers and two-way radios used by Hezbollah operatives—one analyst deemed the unprecedented Israeli operation “the most extensive physical supply chain attack in history.” Ongoing airstrikes in Beirut and southern Lebanon have marked the most significant Israeli barrage in 11 months of tit-for-tat escalation. On September 27, Israel dealt Hezbollah a devastating blow by killing its leader Hassan Nasrallah in an airstrike on a Beirut suburb. Despite reeling from these latest reverses and the evisceration of its command structure, the Shiite militia continues to lob missiles at Israel. Stunned and outraged, Iran—Hezbollah’s patron—fired around 200 ballistic missiles at Israel; at least one person was killed in the West Bank. Iranians are now bracing for Israeli retaliation. The cycle of violence, it appears, is far from over.

This latest episode underscores the near-complete breakdown of deterrence in the Middle East. Both state and nonstate actors are taking huge risks. As a standalone operation, the pager attack could have signaled Israel’s resolve to compel Hezbollah to de-escalate or face a catastrophic war. But Israel’s decisions to assassinate Nasrallah, intensify strikes on Lebanon, and even commence a ground invasion suggest a grimmer possibility: the pager operation was merely meant to put Hezbollah on the back foot as a prelude to a more expansive Israeli military intervention.

For nearly two decades, relative calm has reigned on the Israeli-Lebanese border. But the latest escalation lays bare the reality of a region that has grown profoundly more perilous since Hamas’s October 7 terror attack and the ensuing Gaza conflict. The Middle East is no longer bound by established rules of engagement and modes of deterrence. Assumptions undergirding the behavior and risk calculus of many state and nonstate actors in the region are increasingly obsolete. Clear redlines and mutually accepted rules of the game are glaringly absent. So, too, are reliable channels through which the warring parties can de-escalate.

The United States can rebuild its waning influence and play a decisive role in restoring deterrence in a region where countries and militant groups now feel able to act recklessly. But it has to recognize first that its current policies are inadequate and outdated. It continues to rely largely on conventional military approaches to deterrence that fail to account for the shifts roiling the region: emboldened nonstate actors, unrestrained state actors, and disruptive technologies. Washington must help all parties minimize the likelihood of miscalculation and work to stop the erosion of deterrence that has inflamed violence. If it does not do so, it will risk being drawn into a regionwide conflict with global implications.

AXIS OF OPPORTUNISTS

Nonstate actors have long played a destabilizing role in the Middle East. But after October 7, the loose conglomeration of Iran-aligned groups known as the “axis of resistance” have managed to disrupt the region in unprecedented ways. Just one day after Hamas’s terror attack, Hezbollah began a spate of strikes on northern Israel that forced at least 60,000 Israelis from their homes, effectively creating a five-kilometer buffer zone inside Israel. Israeli retaliatory attacks have exacted an enormous price on Lebanese civilians, displacing hundreds of thousands and killing more than 1,000, with an exponential increase in the death toll since mid-September.

Iranian-backed militias in Iraq also joined the fray last October, targeting U.S. forces based in Iraq and Syria. Several Iraqi militias operating under the umbrella of the Islamic Resistance in Iraq, for example, have undertaken more than 100 attacks against U.S. targets in addition to strikes directed at Israel. Most recently, the IRI claimed responsibility for a drone strike on the Israeli city of Eilat on September 25.

And in November 2023, the Houthis, a Yemeni rebel group, launched an ongoing campaign of attacks on more than 100 merchant ships in the Red Sea, disrupting global trade and resulting in delays and cost increases for container shipping from Asia to Europe and North America. Ever more daring, the Houthis used a drone to attack Tel Aviv in July, killing one civilian and injuring ten others. Israel responded by targeting Yemen’s Hodeidah port, which accounts for 70 percent of Yemen’s commercial imports and 80 percent of its humanitarian aid, crippling the delivery of essential assistance in the war-ravaged country. In September, a long-range missile launched by the Houthis reached central Israel. Later in the month, the group claimed to hit the Israeli cities of Tel Aviv and Ashkelon with separate drone strikes, for which Israel retaliated with large-scale strikes on Hodeidah. The Houthis’ behavior exemplifies the risky and provocative decisions that accompany a breakdown of deterrence, as the concerted military action of the United States and its allies has done little to rein the group in.

The erosion of deterrence in the Middle East has been precipitated by a broader shift: the perception that American dominance in the region is waning. As U.S. policymakers have tried to pivot away from the Middle East, nonstate actors have sought to take advantage, believing that they can now assert themselves more freely in pursuit of their goals. To those ends, they have been buoyed by easier access to drones and missiles and the popular narrative that pits them against Israel and the United States. The October 7 attack propelled them to seize opportunities to cause disruption. Although Israel has delivered both Hamas and Hezbollah severe setbacks, the turmoil unleashed by nonstate actors has illuminated a crisis of deterrence, one that has entangled state actors in the most visible and destructive episodes of unchecked escalation.

OLD FOES, NEW RULES

The breakdown of deterrence has also resulted in direct confrontation between Iran and Israel. Iran’s recent barrage against Israel in retaliation for the Nasrallah assassination is only the latest episode of direct confrontation between the two adversaries. In April, Iran retaliated for an Israeli strike on an Iranian consular building in Damascus that killed several Islamic Revolutionary Guard Corps officers, including two senior commanders, by unleashing a barrage of more than 300 missiles and drones at Israel. The attack upended long-standing rules of engagement that had governed the “shadow war” between the two countries; Iran might seek to hurt Israel through proxies and covert actions, but it would refrain from directly attacking its adversary. With that precedent in mind, Israel mistakenly assumed that Iran’s response to the Israeli attack on its diplomatic compound in Damascus would be limited. But Tehran’s risk calculus had shifted, possibly reflecting the belief among Iranian policymakers that Israel’s increasingly provocative strikes demanded a more forceful, overt response. Iran—the patron and ideological north star of the resistance axis—chose to emerge from behind the veil of plausible deniability afforded by its proxies. But Israel’s response to Iran’s April salvo was telling; it opted for a modest but pointed retaliation, hitting a few targets near sensitive Iranian nuclear and military sites. Even as leaders condoned ever-riskier behavior, none seemed to want the conflict to spiral out of control.

The escalatory cycle continued nonetheless. In the months that followed, both sides ratcheted up attacks. Back-to-back Israeli strikes on Beirut and Tehran in July and a major missile exchange in August raised fears of an all-out war. Israel’s September escalation resurfaced those fears.

Israeli Prime Minister Benjamin Netanyahu, long considered to be fairly risk averse, appears more willing to take greater risks, as evidenced by the assassination of Nasrallah and continued strikes on Lebanon, the audacious intelligence operations against Hezbollah, and the July assassination of Hamas leader Ismail Haniyeh in Tehran. Taken together, these moves suggest that the Israeli leader is ready to gamble that doubling down on military force to restore deterrence and disrupt the threat posed by the axis of resistance outweighs the risks of provoking a regionwide war.

The Middle East finds itself in a dangerous moment. Old conventions governing escalation have been cast aside; new actors have emerged, and all are jockeying for dominance. As a result, the margins for preventing an all-out war are narrower than ever. Most dangerously, efforts to rebuild deterrence are largely limited to the use of force. Each side escalates militarily to deter the other. Failing to respond with force to an aggressive action can invite greater provocation, but so, too, can responding with force beget further escalation. In either instance, violence is more likely to ratchet up uncontrollably.

ENGINEERING PEACE

The United States must reassess its approach to a region in which direct confrontation between Iran and Israel is now a reality and where nonstate actors are undeterred and continue to escalate. To date, a ragtag militia such as the Houthis has ground global shipping in the Red Sea to a halt despite significant U.S. military engagement, and U.S. aircraft carrier groups stationed in the region have not managed to deter Hezbollah from launching unrelenting attacks against northern Israel. Despite its close alliance with Israel and its crucial support for the Israeli military, the United States has been unable to discourage Netanyahu from upping the ante. Washington must develop a new approach that employs all the instruments of U.S. power to address the reality of a new, more perilous Middle East. This new strategy should build on instances in which deterrence and de-escalation have been achieved, even if temporarily, over the last 11 months.

An updated U.S. deterrence strategy for the Middle East should first strengthen and regularize backchannel mechanisms that can mitigate the threat of miscalculation and misunderstanding. The United States can support quiet, third-party mediation through countries such as Oman, which has played a critical role in passing messages between the United States and Iran during moments of high tension. It should also consider the establishment of a network of hotlines among Israel, Egypt, the Gulf states, and Iran to help officials guard against unintended confrontation. States should lean on third parties with direct ties to proscribed groups, including state actors such as Qatar and political actors such as Shiite leader Nabih Berri in Lebanon, to maintain lines of communication with nonstate actors. For the gravest instances, the United States should have an established direct hotline with Iran.

Although the United States has sometimes relied on them too much, economic sanctions can be an effective tool for U.S. policy in the region as long as they are appropriately coordinated and calibrated. Before imposing new sanctions, the United States should find ways to better enforce the sanctions that are already in place, including developing more creative efforts to end the sale of U.S.-sanctioned Iranian oil to China using “dark fleet” tactics, in which ships disable their tracking capabilities to avoid detection. Washington should also deepen intelligence sharing with friendly countries and more concertedly craft plans with European allies for coordinated actions targeting Iran’s ballistic missile and drone programs, similar to the joint U.S. and EU efforts to ratchet up pressure on Iran announced in September, following Iran’s transfer of short-range ballistic missiles to Russia.

The United States can help deter violence in the region by strengthening its own military capabilities. Counterdrone and missile defense technology proved essential to halting the April escalation between Iran and Israel. Yet these weapons are continually evolving. The United States should prioritize the innovation of this technology by deepening private-sector partnerships, rewarding creativity in manufacturing, and shortening the timeline of these weapons from conception to production at scale. It should also harness artificial intelligence and even certain technologies used in computer games to better anticipate threats and develop the most effective responses to volatility in the Middle East.

Before any missiles are fired, however, Washington should recognize the foundational role of diplomacy in building deterrence. An effective diplomatic strategy for the region will reestablish deterrence not just by threatening and coercing others, but also by creating positive incentives that would eschew conflict. Just one year before the devastating October 7 terror attack, Israel and Lebanon reached a historic maritime border deal with the help of skillful U.S. diplomacy and the promise of real benefits for both parties. Each side hoped to exploit valuable natural gas assets in the Mediterranean. Settling the maritime border issue eliminated a source of contention that could otherwise have led to hostilities that would have invariably undermined those natural gas ventures. More broadly, vesting disruptive nonstate actors with something to lose could turn their risk calculus away from violence and toward peace and reconciliation. To further tamp down conflict in the Middle East, the United States should help facilitate a regional security architecture in the form of security partnerships and cooperation agreements among like-minded countries, a mediating mechanism and forum for the peaceful resolution of conflict sorely missing in the most strife-ridden region in the world.

In the absence of these reforms, the status quo is untenable. Outdated models of deterrence have failed in a twenty-first century Middle East where nonstate actors have easy access to drones and other technologies at the cutting edge of warfare. Only reconfiguring the existing U.S. approach to deterrence in the Middle East will avert catastrophe.