Countering the Swarm

Executive Summary

After decades of air dominance and a near monopoly on precision strike, the United States now faces a dramatically different, more hostile world as the proliferation of cheap drones has democratized mass precision fires. It is likely that in any future conflict, drones will pose an unavoidable threat to American forces.

As this report’s analysis of U.S. defense spending reveals, the Department of Defense (DoD) has invested in both legacy and emerging counter–uncrewed aerial systems (C-UAS) capabilities for nearly a decade. However, these efforts have been hindered by insufficient scale and urgency. Despite the Pentagon’s shortfalls in procuring purpose-built C-UAS capabilities, U.S. counter-drone operations in the Middle East have been notable.

The United States views China as its foremost strategic threat, and the People’s Liberation Army (PLA) is rapidly advancing its drone capabilities by developing more autonomous systems and acquiring them at scale. Without deep magazines of substantially enhanced counter-drone capabilities, the United States risks having its distributed warfighting strategies overwhelmed by massed Chinese drone attacks, and the United States could lose a war over Taiwan. This is a complex challenge with no silver bullet solution. The DoD must act swiftly. The stakes are not theoretical—without adequate defenses, even the most advanced systems and tactics will be rendered irrelevant in the face of overwhelming drone attacks.

Overall Recommendations for the Department of Defense

Prioritize counter-drone defense and extend capabilities beyond the air defense community.

Drone defense cannot be siloed to dedicated air defense units. Every unit will need the ability to defend itself against small uncrewed aerial systems (UAS).

Expand counter-drone training across the Joint Force.

The Pentagon needs to develop and share best tactics, techniques, and procedures and ensure that all forces are trained in drone self-protection.

Improve the rigor and realism of counter-drone prototype testing.

The current test and evaluation process fosters a false sense of confidence in prototype counter-UAS, as they are often assessed using unrealistic facsimiles of enemy drones and low-fidelity tests of electromagnetic weapons.

To Be Prepared for Today’s Drone Threat, the DoD Must Invest in Proven Capabilities

Build resilient defenses with layered active defenses and passive countermeasures.

U.S. forces must be operationally resilient, meaning they have the ability to defeat or absorb drone attacks while continuing with their other missions. Resilience requires layered active defensive systems with multiple different types of sensors and effectors.

Given that no air defense system can provide complete protection at all times, integrating passive defense measures is essential to achieving operational resilience.

Strengthen mobile counter-drone capabilities and tactics for maneuvering forces.

The United States has not developed appropriate mobile defense for maneuver formations, nor has it fielded sufficient handheld capabilities for dismounted infantry.

Procure large stockpiles of high-volume, short-range kinetic interceptors.

High-volume air defense solutions incorporate emerging technologies such as high-power microwaves (HPM) and directed energy systems, which do not rely on interceptors. However, expanded use of immediately available gun-based systems and low-cost rocket interceptors, such as the Advanced Precision Kill Weapon System, is also needed.

To Be Prepared for the Future Drone Threat, the DoD Must Also Invest in Emerging Capabilities

Invest in AI-enabled processing of sensors and AI command and control to speed up C-UAS kill chains.

Integrating the command and control of diverse counter-drone systems and leveraging artificial intelligence (AI) to accelerate threat identification and engagement is essential for improving defense effectiveness while also advancing the Pentagon’s vision of Joint All-Domain Command and Control (JADC2).

Transition promising rapidly emerging technologies, especially high-power microwaves, to programs of record.

HPM is the technology most capable of defeating swarms and high-volume attacks.

Invest in high-resolution passive sensors.

Long-range, high-resolution passive sensors offer a survivable alternative to active radars for finding drones and have the potential to enhance the defender’s advantage.

Introduction

On October 17, 2023, Iranian-backed militias launched two one-way attack drones—better known as kamikaze drones—at al-Asad Airbase in western Iraq. U.S. forces swiftly shot down one drone; the other, though damaged, slipped through defenses and injured several American troops.¹ At the same time, Harir Air Base in northern Iraq was targeted by a militant drone, but U.S. forces intercepted it before it could do harm.² The next day, U.S. personnel at Syria’s al-Tanf Garrison stopped one incoming drone, but another evaded defenses and made impact, inflicting minor injuries.³ On October 19, Yemeni Houthi rebels launched drone attacks on Israel, thrusting the USS Carney (DDG-64) into a 10-hour battle that would become “the most intense combat engagement by a U.S. Navy warship” since World War II.⁴ These drone strikes surprised American forces, and marked the beginning of what one expert described as a new type of guerrilla warfare.⁵

In each instance, the individual attacks were unremarkable—only one or two drones or missiles—and most were defeated by skilled American operators employing sophisticated air defenses. However, the frequency and scale of the drone strikes that began in October 2023 was not something U.S. troops had previously experienced. Although U.S. forces performed incredibly well under fire, the cumulative impact of these sustained attacks has been significant: injuring U.S. personnel, depleting U.S. air defense interceptor stockpiles, and degrading readiness.

Since 2004, the proliferation of Iranian drones to Tehran-backed proxy forces has made these attacks possible and has profoundly transformed the Middle Eastern battlefield.⁶ Iranian systems are cheap enough to be bought in large quantities, yet capable enough to hit their targets from hundreds of miles away. While proxies traditionally have relied on inaccurate missiles, rockets, and mortars, Iran’s drones are precision weapons that can be acquired en masse. These “precise mass” cheap drones have put U.S. forces at risk, eroding the longstanding U.S. precision strike advantage and enabling adversaries to impose disproportionate costs on the United States.⁷