The Attacks Beyond Gaza

Yemen’s Houthi movement surprised Middle East watchers when it fired drones and cruise missiles at Israel on October 19. Few had expected the group’s saber rattling to be much more than words, considering how inaccurate most of the Houthis’ long-range weapons are, not to mention their history of empty threats against Israel. Some assumed, incorrectly, that the USS Carney’s interception of those munitions would deter subsequent efforts.

Yet the continued Houthi attacks—at least ten separate ones to date—demonstrate the Houthis’ full integration into Iran’s informal regional alliance, the Axis of Resistance, and the extent to which Iran’s arming of its proxies has transformed regional security dynamics. For Israel and the United States, the Axis of Resistance’s expansion and activation in the Israel-Hamas conflict has been a complicating factor as they seek to contain the fight to Gaza.

Iran has been actively cultivating ties to the Houthis for over a decade. With limited investment, Iran has transformed the Houthis from a local armed opposition group to one able to project power regionally. The 2014–15 outbreak of Yemen’s civil war, which coincided serendipitously with positive trend lines for Iranian interests in Iraq and Syria, created an opportunity for the Quds Force, the clandestine wing of Iran’s Islamic Revolutionary Guards Corps (IRGC), to move some of its more experienced senior operatives to Yemen.

Prior to this period, it was senior Hezbollah operatives who were the primary Iranian agents working with the Houthis. But Houthi leadership was also actively courting Iranian support, both from a pragmatic position and from a shared principles position: Iran’s revisionist behavior and its revolutionary model were attractive to Houthi leaders, who incorporated the ideology into their fundamentalist take on Zaydi Islam. (Zaydism emerged in the 8^th century as a branch of Shia Islam and is prevalent in northern Yemen.) Pragmatically speaking, Houthi leadership saw no other potential regional partner.

Quds Force officers have orchestrated the transfer of increasingly sophisticated and longer-range weapons that the Houthis have used in the meantime against Saudi Arabia. In 2015, the Houthis were mostly using munitions from the Yemeni military’s arsenal—the most advanced of which were some aging Scuds. Within a few years, the Houthis were fielding an array of drones serving different tactical purposes—especially an assortment of short- and long-range one-way “kamikaze” attack drones—and also ballistic and cruise missiles with increasing ranges. The arrangement was mutually beneficial: the Houthis battlefield tested Iranian-sourced weapons that gave them an asymmetrical edge (including against Saudi Arabia’s Patriot air defense systems and even the UAE’s THAAD missile defense system) while enabling the Quds Force to further refine and develop these capabilities. The Houthis and other Iranian-backed Iraqi militias had already provided successful use cases by the time that Iranian drones surfaced in Ukraine in October 2022.

Arming the Houthis was never just about leveraging a proxy in Iran’s ongoing conflict with Saudi Arabia; it was always also about adding depth to the Axis of Resistance while opening new threat vectors against both Israel and also the United States. Long-established Iranian-backed groups such as Lebanese Hezbollah, Hamas, and even Palestinian Islamic Jihad have served as a deterrence against an Israeli strike on Iranian nuclear facilities.

Simultaneously, Iraq-based groups backed by Iran have sought to drive the United States out of the region. For example, Kataib Hezbollah and Asa’ib Ahl al Haq attacked U.S. troops during the 2000s, strengthened themselves significantly during the counter-ISIS campaign, and then resumed direct attacks on U.S. troops in the late 2010s in efforts to expel America from Iraq.

Currently, the Houthis not only complicate Saudi Arabia’s security calculus but also those of America and Israel. The former’s weapon range, however inaccurate, covers southern Israel, the Arabian Peninsula, and the Horn of Africa. Lacking precision does not mean the weapons are not deadly—even an imprecise strike can impose costs. The Houthi threat increases the defensive posture that U.S. troops must sustain in regional bases such as Camp Lemonnier across the Red Sea in Djibouti and al Dhafra air base in the Unite Arab Emirates. And it narrows the use of Israeli air defense systems to defending against attacks from the south, drawing on finite defenses that could otherwise serve to limit the impact of a Hezbollah offensive from the north. Finally, having access to the waterways surrounding Yemen enables Iranian-led escalations against Israeli maritime vessels (including commercial) while also adding to potential hazards for maritime traffic through the strategic chokepoint of the Bab al Mandab Strait.

Israel and the United States must now navigate the new reality of the proliferation of Iranian-sourced weapons and capabilities. Iran has coordinated actions taken among its various proxies, including the recent attacks against U.S. bases in Iraq and Syria and the Yemen Houthis’ activities, seeking both to impose costs on the United States for supporting Israel and also to limit additional U.S. assistance, while additionally seeking (unsuccessfully) to deter Israel from launching a ground offensive in Gaza. To date, Iraq-based groups have attacked U.S. forces at least sixty-six times in Iraq and Syria since the start of this conflict, injuring over sixty troops. The Houthis, in addition to the attacks against Israel, have also shot down an MQ-9 Reaper drone off the western Yemeni coastline, seized the Galaxy Leader (a ship partly owned by an Israeli company), and fired missiles near the USS Mason after it responded to a distress call from a commercial ship. 

This multi-front attack campaign, staged from Iraq and Yemen, is exactly what the Quds Force had always sought to build by supporting the various members of the Axis of Resistance.

Despite the Quds Force's years-long plan, the scope and scale of the recent attacks seems to have caught the U.S. military somewhat off-guard. The threat to U.S. forces operating in Iraq and Syria is hardly new—they have had to defend against such drone and rocket attacks previously. But the steady pace of attacks is a change.

Thus far in response, the U.S. military has struck Iran-linked bases and facilities in Syria on three different occasions and Kataib Hezbollah facilities in Iraq. But this fits the well-established tit-for-tat pattern that has not prevented subsequent attacks. Almost certainly, the so-called Islamic Resistance in Iraq, the unified name under which Iranian-backed Iraqi groups are currently operating, now perceives Syria-based assets as expendable while keeping high-value targets in Iraq away from military positions and out of the equation—for now. And while a suspiciously timed internet outage occurred in Yemen hours after a Houthi attack on Eilat, Israel, neither the United States nor Israel has responded directly to such belligerent activities, seemingly in an effort to contain the spiraling conflict.

The takeaway for Iran and the Axis of Resistance members is that they can engage in this carefully metered escalation against Israel and the United States without bearing significant costs.

While the Pentagon continues to message that it reserves the right to respond to attacks at the “time and place of [its] choosing,” its actions have yet to prevent groups from resuming their attack patterns. Iran’s challenge thus remains unmet. Secretary Austin’s call for these attacks to cease, and his threat to do “what’s necessary” to protect U.S. troops, reveals the punitive rather than deterrent nature of U.S. actions against Iranian-backed groups. Why, then, would these groups change their approach?

Until the United States accepts that Iranian-backed groups have already weighed the costs of potential retaliatory strikes and are undetered by them, the U.S. military—and its regional partners—will remain on the defensive. The current dynamics will only embolden Iran, which has been able to pull the strings unscathed from afar. And while such a posture might be what it takes to prevent a wider war for the time being, it does not bode well for when the United States will be forced to assert and protect its own interests in the region.

Katherine Zimmerman is a fellow at the American Enterprise Institute and advises AEI’s Critical Threats Project. Follow her at @KatieZimmerman.

Image: The USS Carney fires a Standard Missile 2 to defeat a combination of Houthi missiles and unmanned aerial vehicles in the Red Sea, Oct. 19, 2023. (U.S. Navy)