The case for a layered missile defense of the US homeland
© U.S. Missile Defense Agency

During this time of uncertainty, Americans should be confident knowing our country already has protection against a very different type of threat: every hour of every day, 44 Ground Based Interceptors (GBI) split between Alaska and California are ready to defend all 50 states against incoming intercontinental ballistic missile (ICBM) attacks by rogue states. Inside U.S. command and control centers, military operators dutifully stand watch, ready to carry out a high-stakes defense of the homeland – a mission often described as “hitting a bullet with a bullet.”

While we are confident in our ability to defend the homeland against current missile threats by rogue states, the risks are anything but static. Launch-after-launch, our adversaries are learning and adapting through trial and error. The United States must constantly stay ahead of this threat to keep our homeland from becoming vulnerable to foreign coercion or attack. Letting our guard down would threaten U.S. alliances and limit options during a crisis, while stronger defenses give our leaders a margin of safety that enables them to more effectively negotiate disputes.

To stay ahead of these threats, the Department of Defense (DoD) is taking a number of steps, now and in the future. For starters, DoD is ensuring the reliability of the existing 44 GBIs, extending their service life through regular testing and performance upgrades. We’ve also initiated a new program to develop a Next Generation Interceptor (NGI) to improve homeland missile defense performance against evolving threats. When fielded between 2028 and 2030, at least 20 new NGIs will sit alongside the existing GBI fleet for a total mix of 64 defensive interceptors.


To complement these capabilities and provide extra layers of protection between now and 2028, DoD is also exploring near-term options to augment the GBIs and future NGIs. Later this year, the Missile Defense Agency (MDA) will conduct an intercept test of a “Standard Missile” (SM)-3 Block IIA – originally designed to engage medium or intermediate range threats – in order to verify its ability to successfully engage a longer range, ICBM-class threat. MDA is also evaluating the technical feasibility of employing interceptors from another system – the Terminal High Altitude Area Defense (THAAD) – as a possible homeland defense against incoming long-range missiles in their final (terminal) phase. These additional homeland defense layers, should they prove feasible, could be available by mid-decade and reinforce America’s protection against a rogue state missile attack.

But missile defense involves more than just shooting interceptors at incoming targets. It’s also about using sensors to detect the threat early in the launch cycle and communicating data seamlessly between sensors and interceptors. That is why DoD is simultaneously investing in the development of a new generation of advanced ground- and space-based sensors. Having the ability to detect, track and “discriminate” (i.e., differentiate a real warhead from a decoy) accurately allows precious time and is what truly enables missile defense interceptors to hit their targets. Our capabilities will be significantly upgraded later this year with the completion of a ground-based long-range discriminating radar in Alaska, and we are also actively developing a new defensive network of space-based sensors to track more sophisticated missile threats. A comprehensive network of space-based sensors is particularly important because it offers an “over the horizon” perspective of in-flight missile trajectories, something geographically fixed ground sensors cannot provide.

A layered homeland defense, however, is not only useful when the missiles are flying, it also plays a role in deterring potential adversaries. Having multiple missile defense options at our disposal complicates missile attacks being contemplated by adversaries, creating uncertainty about the potential success of their plans. Although avoiding conflict will always be our preferred approach, a layered homeland missile defense offers contingency in a worst-case scenario and gives our leaders leverage to negotiate from a position of strength, safe from the specter of coercion.

Despite these advantages and the relatively limited quantity of interceptors we possess, critics claim that U.S. efforts to diversify its homeland missile defense are destabilizing and causing an arms race with China and Russia. This critique is routinely promoted by officials in Beijing and Moscow despite understanding that U.S. missile defenses are built to defend against comparatively limited rogue state attacks, not against China and Russia which possess much larger strategic arsenals. To address the threat of a comprehensive and technologically sophisticated strategic attack by China or Russia, the United States relies on the same strategy it has employed for more than half a century – nuclear deterrence, not missile defense.

These well-known facts don’t prevent Beijing and Moscow from engaging in political doublespeak to pursue their national interests. While China and Russia claim without blushing that only U.S. missile defenses represent a threat to world order, both countries are actively building their own missile defense systems against all types of threats. For example, Russia is in the process of upgrading its ballistic missile defenses around Moscow. Even more disturbingly, the dozens of ballistic missile interceptors making up Russia’s defenses have nuclear-armed tips, rather than the conventional interceptors employed by the United States. The goals of this international disinformation campaign are clear: sow domestic and international division, while leaving the U.S. homeland more vulnerable to coercion and attack. The United States has the sovereign right, and duty, to defend itself – and we will do nothing less.

At the end of the day, the question we must ask ourselves is whether the U.S. homeland is safer with or without a layered missile defense system designed to counter an ICBM arsenal under the “control” of an unstable, rogue adversary. Since there is only one real choice, it is critical for the United States to stay ahead of current and future threats, which multiply in scope and complexity each year. With the support of Congress, we can meet this challenge.

Robert Soofer, Ph.D., is Deputy Assistant Secretary of Defense for Nuclear and Missile Defense Policy.