Ten Ways Hypersonic Weapons Can Strengthen Strategic Deterrence

The Department of Defense is funding at least eight programs aimed at equipping each of the military departments with hypersonic weapons by the end of the decade.

Hypersonic systems are designed to fly at velocities of five times the speed of sound or greater. Unlike ballistic missiles, their flight paths are mainly within the atmosphere and they can maneuver in unexpected ways.

Their speed, relatively low operating altitude and lack of a predictable trajectory make them exceedingly difficult to intercept until they are in the immediate vicinity of their intended targets—which leaves defenders little time to act.

The hypersonic weapons being developed by the Pentagon are different from those being tested in Russia and China, because the U.S. weapons are not designed to carry nuclear warheads. The kinetic force generated by their speed at impact is sufficient to destroy many types of targets.

All of these features make hypersonic systems a unique class of weapons, and policymakers have only recently begun to think through how they might be used.

The tendency is to treat them like a new category of tactical system, and that impulse is reinforced by the fact that their ranges are similar to those of existing cruise missiles (1,000-2,000 miles).

However, the hypersonic weapons expected to be fielded by the joint force later in this decade can make a significant contribution to strategic deterrence—traditionally the province of nuclear strategists.

Although analysts are not accustomed to thinking of non-nuclear systems as contributors to strategic deterrence, this year’s Nuclear Posture Review states that “non-nuclear capabilities may be able to complement nuclear forces in strategic deterrence plans.”

With that in mind, here are ten ways that the unique characteristics of hypersonic weapons might strengthen the strategic deterrence posture supported by America’s nuclear triad.

1. Retaliation is assured. Deterrence is a psychological state grounded in the adversary’s fear of consequences. The whole point of U.S. deterrence plans is to convince an enemy it will suffer unacceptable damage in response to an act of aggression. Hypersonic weapons bolster an adversary’s fear of retaliation by introducing a class of weapons against which defense is extremely difficult. Their path is unpredictable and thus defenders are left with little or no time to intercept attackers.

2. Responses are proportional. U.S. nuclear strategy posits that effective deterrence requires responses calibrated to the scale of enemy aggression. It is counterproductive to respond to a limited attack with heavy retaliation, because that might quickly drive an adversary up the “ladder of escalation.” Hypersonic weapons provide new retaliatory options on the continuum of conflict that enable U.S. forces to respond in a precisely proportional manner to whatever provocation an adversary mounts.

3. The nuclear threshold is raised. The Nuclear Posture Review states that in some cases strategic aggression might not involve the use of nuclear weapons. Washington thus might have to choose between an inadequate conventional response or being the first to use nuclear weapons in an exchange. That could prove to be self-deterring for leaders who understandably fear crossing the nuclear threshold. Hypersonic weapons make it easier to fashion strategic responses without “going nuclear,” thereby forcing the fateful choice of nuclear first use on the adversary.

4. Escalation is controlled. Many of the warfighting scenarios supporting U.S. nuclear plans envision conflicts that begin at the conventional or limited nuclear level and then gradually escalate. Escalation typically occurs when the side that is losing decides to employ an increased increment of force (violence). By providing additional gradations of force that fill gaps in in the panoply of response options, hypersonics make it more likely U.S. warfighters can restrain and shape the escalatory process until the adversary reaches a point where it fears going further.

5. Credibility is bolstered. Because deterrence is at base a psychological state, perceptions are critical to its success. The adversary must believe that retaliation is likely, otherwise a deterrent posture won’t work. That is why Putin’s nuclear threats haven’t gotten him much in Ukraine—Western leaders doubt he would actually use weapons of mass destruction. Hypersonic weapons make the threat of retaliation more credible because they can reliably target key assets without leading to game-changing destruction. The enemy is thus more likely to believe the threat of retaliation is real.

6. Allies are reassured. A key goal stated in the Nuclear Posture Review is to strengthen extended deterrence, meaning the security guarantees given to overseas allies and partners. U.S. allies have long feared that in a nuclear showdown, America might be unwilling to risk New York in order to protect London or Paris. But the threat of U.S. retaliation is more plausible when Washington can accomplish strategic objectives without putting its entire homeland at risk. In other words, the availability of hypersonic weapons doesn’t just bolster the credibility of deterrence among enemies, but also among friends.

7. Effects are tailorable. Hypersonic weapons can help U.S. military planners to tailor retaliation to the specific circumstances surrounding a provocation. This is about more than the proportionality of responses, it is about the personalities of enemy leaders, the political culture of their country, and other factors contributing to how they interpret military actions. For instance, the Kim family that controls North Korea will have a different take on certain types of responses than the theocratic leaders of Iran. Hypersonics enable effects that can be an exact match to the sensibilities of target audiences.

8. Collateral damage is minimized. Nuclear weapons, by their nature, are gross instruments. Thus, their use is always accompanied by the potential for unintended damage. Such damage can interfere with the messaging intended by the selection of specific retaliatory options. Whatever the U.S. was trying to convey can be thoroughly confused by the collateral damage that is caused. With hypersonic weapons, unintended damage is minimized while intended targets are destroyed, so the retaliation is more likely to be interpreted as planned.

9. Conventional attacks are discouraged. The Nuclear Posture Review warns that “some Allies and partners are particularly vulnerable to attacks with non-nuclear means that could produce devastating effects.” That observation underscores the linkage between conventional and nuclear weapons, because in some situations adversaries need not use nuclear weapons to accomplish strategic outcomes. It is vital to have response options appropriate to the scale and intensity of aggression across the spectrum of conflict, even if the aggression is not nuclear. The availability of hypersonic weapons enhances the deterrence of conventional violence aimed at strategic goals.

10. Armageddon is more readily averted. Nuclear war is one of the few dangers that can destroy America in a day, and arguably the only one that can be initiated by human action. No national purpose is more important than deterring such a conflict. But strategic deterrence can collapse due to many causes—calculated aggression, intelligence failure, diminished leadership capacity, command breakdown, etc. In all such scenarios, it is valuable to have response options that can bring hostilities to an early end before civilizations are destroyed. The unique features of hypersonic weapons provide capabilities that might prove relevant to circumstances seldom gamed or even envisioned.

To summarize all of the above, hypersonic weapons—with their combination of assured penetration, tailored effects and credible utility—have the potential to make a significant contribution to strategic deterrence. They will never replace nuclear weapons in the deterrence calculus, but they can make the use of America’s most fearsome warfighting systems less necessary even in extreme circumstances.

Several companies involved in developing hypersonic weapons contribute to my think tank.