Denial or Punishment? The U.S.-Israel Debate About How Best to Deter Iran

Iran’s decision to launch a direct, state-on-state attack against Israel on April 13 increased the risk of overt conventional conflict in the Middle East. This attack was significant in scope, scale, and complexity, employing hundreds of one-way attack drones, cruise missiles, and ballistic missiles. Equally significant was the U.S.-organized effort to defeat Iran’s attack, working with Israel as well as European and Arab allies to integrate capabilities and defend the region’s airspace. Although not publicly claimed, the April 19 Israeli response targeted air defenses protecting Iran’s nuclear program deep inside the country, without damage to civilian infrastructure or civilian casualties. And while the April 2024 escalation cycle appears closed, the region has now crossed the threshold for state-on-state attacks, with Israel and Iran both displaying potent capabilities and resolve.

The following article is part of a new series that aims to shed light on the opportunities and risks of the post-April 13 strategic environment.

Differences over how Israel should respond to challenges by Iran following its drone and missile attack of April 13 have become the latest source of U.S.-Israel tensions. Israeli officials pledged—both before and after the strike—to respond by hitting Iran. By contrast, President Biden urged Israel to “take the win” and avoid further action. Israel’s limited strike on an Iranian air-defense site on April 19 shows that it remains determined to deter Iran by denial as well as punishment. (Denial works by convincing the adversary that it will be thwarted, punishment by convincing the adversary that it will incur unacceptable costs.)

The United States has increasingly relied on deterrence by denial in recent years to counter Iran’s destabilizing regional activities. It has bolstered regional air and missile defenses and stood up maritime task forces to persuade Tehran that its attacks will be disrupted and its goals frustrated. Conversely, it has generally eschewed military activities that could impose costs on Iran, but which might be perceived as escalatory. Israel, by contrast, is at greater risk due to its proximity to Iran, and it therefore prefers to include in the mix deterrence by punishment in order to disrupt Iranian activities and impose costs.

Despite Washington’s preference for deterrence by denial vis-a-vis Iran, America’s own experience shows that a balanced strategy that blends both denial and punishment—to thwart Iranian activities and hold at risk or destroy assets that it values—is a more effective way to deter and contain the Islamic Republic.

Denial and Punishment: Historical Insights

The United States has more than forty years of experience trying to deter Iran and disrupt its destabilizing regional activities. These efforts have, however, borne mixed results, highlighting the limitations of deterrence by denial.

Proxy warfare vs. U.S. troops in Iraq and Syria (2003-present). In recent years, U.S. forces in Iraq and Syria have relied largely on various defensive measures to enable them to accomplish their mission in the face of attacks by pro-Iran militias. These include passive force-protection measures such as the hardening of facilities and dispersion of forces; rules of engagement that permit forces to return fire when attacked; and ground-based air and missile defenses—augmented by defensive fighter patrols. U.S. forces generally launched offensive airstrikes only after U.S. personnel were killed or wounded, following close calls, or to preempt or disrupt planned attacks.

Thus, since the start of the Hamas-Israel war on October 7, pro-Iran proxies have launched over 170 drone and rocket attacks on U.S. forces in Iraq and Syria, while the United States responded about ten times—hitting increasingly consequential targets—until three U.S. soldiers were killed in a drone attack on a logistical site in Jordan in late January. This prompted an unusually large U.S. airstrike on proxy facilities linked to the Islamic Revolutionary Guard Corps (IRGC) in Iraq and Syria and a drone attack on a senior militia commander in Baghdad in early February, leading to a twelve-week halt in attacks in Iraq and Syria that ended last weekend.

In 2019, during the Trump administration, pro-Iran militias attacked U.S. troops in Iraq around twenty-five times without provoking a U.S. military response. Attacks became more frequent and intense until they killed a U.S. military contractor in late December of that year. Thus began a chain of events that culminated in the U.S. drone strike that killed IRGC Qods Force commander Qasem Soleimani in January 2020. Retaliation—in the form of an Iranian missile strike on U.S. troops at al-Asad Air Base in Iraq and a series of rocket attacks by pro-Iran proxies—was followed by several months of relative quiet.

This echoes the U.S. experience in Iraq from 2003-11, when the IRGC-QF armed, trained, and financed Iraqi militias and insurgents that killed more than 600 U.S. troops. Washington sought to disrupt Tehran’s efforts while avoiding escalation. U.S. and coalition forces regularly interdicted Iranian arms shipments and eventually detained several senior Qods Force operatives, who were subsequently released. The United States also quietly threatened to respond militarily to proxy attacks on the U.S. embassy in Baghdad in April 2008 and against U.S. bases in Iraq in June 2011 (the latter actions killed fifteen U.S. troops). In both cases, attacks stopped after the United States issued stern warnings. While U.S. efforts failed to halt proxy attacks entirely, the threatened use of force (when deemed credible) had a salutary, if temporary, effect.

Gulf tanker reflagging operations (1987-88). U.S. efforts during the Iran-Iraq War to counter Iranian small boat attacks by reflagging and escorting Kuwaiti oil tankers (Operation Earnest Will) demonstrated the efficacy of deterrence by denial and punishment. U.S. military planners initially thought that the presence of a carrier battle group in the region would deter Iran—but in the very first convoy, a reflagged tanker hit a mine. The United States chose not to respond, thereby emboldening Iran, which thereafter relied largely on indirect means (naval mines and attacks on unescorted ships) to prosecute the tanker war. Tehran did not pull back until after a series of surface actions in April 1988 (Operation Praying Mantis) resulted in the U.S. Navy sinking several Iranian warships. American intervention thus deterred direct attacks on reflagged tankers, forced Iran to rely on less effective tactics, and—in tandem with a series of devastating Iraqi victories on land—helped end the war.

“Deterrence by detection”—denying Tehran the benefits of surprise and plausible deniability. Tehran has sometimes deferred or canceled attacks when its adversaries demonstrated foreknowledge of them. Thus, in May 2019, Tehran canceled a planned attack using missiles mounted on dhows after the plan was disclosed to the media; instead, an Iraqi proxy group launched a cruise missile attack on Saudi Arabia’s East-West Pipeline several days later. Likewise, after CENTCOM established a multinational maritime security force in the Persian Gulf in September 2019, attacks on shipping dropped precipitously as increased surveillance reduced the possibility of plausible deniability. And in November 2022, a planned attack on Saudi Arabia’s oil infrastructure was apparently scotched after U.S. and Saudi forces were alerted and the press was notified of the plot. Thus, Tehran may sometimes be deterred when denied the benefits of surprise and deniability, though when honor and interest are at stake, as on April 13, the need to act may override all other considerations.

In sum, U.S. attempts to deter by denial have often yielded to deterrence by punishment, as restraint frequently emboldened Tehran; by practicing both denial and punishment, Washington might more effectively deter and contain Iran. And while the fear of escalation is understandable, it is overstated. The United States and Israel have sparred with Iran for decades without sparking an “all-out regional war,” and recent exchanges indicate that all parties remain interested in avoiding a broader conflict.

Toward a More Balanced Strategy: Denial and Punishment

Tehran is a determined adversary that relentlessly tests limits and works to erode or circumvent adversary red lines. Though it may back down when dealt with firmly, it often seeks alternative means to achieve its goals. A successful deterrence strategy, then, will oblige Iran to act less often and less effectively. Deterrence strategies that rely solely on denial, however, enable Tehran’s traditionally cautious leadership to better calibrate risks and calculate costs, and to wager only those assets it considers expendable. Because denial imposes no costs on it, Tehran can play this game indefinitely.

A more sustainable approach. Iran has waged a decades-long struggle against the United States and its allies that shows no signs of abating. Deterrence by denial allows Tehran to set the terms of engagement and impose costs on its enemies with impunity. Because the United States is a global power with worldwide commitments, it will always face resource constraints and senior leader bandwidth challenges as it seeks to sustain focus on Iran. Washington should therefore work with Israel and Arab partners to implement a balanced strategy that blends both denial and punishment, leveraging Israel’s greater risk acceptance to advance shared objectives. For such a strategy to succeed, U.S. policymakers will need to overcome their debilitating caution and avoid disclosing Israeli activities that the latter has not acknowledged; Arab policymakers should be strongly encouraged to stay the course regarding their participation in the regional air and missile defense architecture created by CENTCOM; and Israeli policymakers will need to act with greater prudence to avoid provocative moves that could stoke U.S. fears of escalation and undermine its support for a more risk-acceptant deterrence strategy. While deterrence by punishment will sometimes require overt action (such as Israel’s April 19 airstrike), a return to gray zone activities (including sabotage, stealthy strikes, unacknowledged overt attacks, or cyber operations) could limit the potential for escalation.

Back to the gray zone. By operating in the gray zone, the United States and Israel would be giving Tehran a taste of its own medicine, enabling them to test Iran’s risk and response thresholds to see what they can get away with; erode and circumvent the Islamic Republic’s red lines (see below); and create uncertainty in the minds of Iranian decisionmakers about how to respond to ambiguous events (such as industrial accidents that might in fact be acts of sabotage). This would also enable them to counter an increasingly risk-acceptant regime in Tehran that attempted— through the April 13 attack—to establish, according to IRGC commander Hossein Salami, “a new equation” with Israel in which “any attack” on “people, property, or interests” will prompt “a reciprocal response from...Iran.” America’s adversaries are watching how it handles the aftermath of that attack; Washington’s willingness to adopt a strategy based on denial and punishment—demonstrating a degree of risk tolerance—could help dissuade Iran from attempting a nuclear breakout and might have a salutary effect on the military calculations of China, Russia, and North Korea going forward.

Michael Eisenstadt is the Kahn Senior Fellow at The Washington Institute and director of its Military and Security Studies Program.