Hypersonic missiles: Three questions every reader should ask

This article is a cross-post from the Bulletin of Atomic Scientists

By Ivan Oelrich, December 17, 2019

Interest in hypersonic weapons is taking off. The United States has for decades supported a modest research effort in such weapons, but now, spurred along by Russia and China, it’s ramping up efforts. Russian President Vladimir Putin used his 2018 address to the nation to announce the development of a hypersonic glider that he claimed would be able to get through all US defenses, and that weapon assumed combat duty this month. Meanwhile, even a cursory scan of the academic research literature shows a healthy presence in this field at Chinese universities, and the hypersonic DF-17 missile was all the rage at that country’s 70th anniversary parade in October. Michael Griffin, head of the Pentagon’s research and engineering, has stated that hypersonic weapons, and defense against them, were the military’s highest technical priorities.

Interest from the press has followed. Scan Google News for the word “hypersonic,” and three times as many hits come up in the last two years as in the previous two-year period. Several reports have appeared in the New York TimesWashington PostEconomist, and other leading general-interest publications, plus many more examples in the trade press.

One thing that jumps out from almost all of these pieces is a glaring lack of normal journalistic skepticism (with a few admirable exceptions). Indeed, some major pieces are downright fawning. The authors readily accept advocates’ claims that hypersonic weapons will move at blinding speeds, have extended range, be easily maneuverable, and strike targets with high precision without considering the engineering challenges or inherent physical limitations that will make this combination of capabilities difficult—if not impossible.

Why do reports on hypersonic weapons generally range from kid-glove treatment to cheer-leading? There are a few different things going on here. Hypersonic vehicles are really impressive and it is easy to be dazzled by their performance (or, more precisely, the performance that is claimed for them). After all, who doesn’t love Formula 1 racecars, speedboats, and anything else that moves fast? Aircraft that can fly through the air with such speed that bits of it start to glow red have an intrinsic appeal.

Analysts should, of course, see past the dazzle. But that reveals another great challenge for reporters covering this topic: the dearth of outside expertise or contrary views. Virtually anyone in the United States who has a solid technical understanding of hypersonic aerodynamics is working for the Defense Department, one of the national laboratories, a contractor working for Defense, or is a university researcher supported at least in part by Defense Department grants.

To be clear, this does not mean that the people doing this work and claiming great virtues for hypersonic vehicles are shills for something they know is nonsense. Quite the opposite. Why would anyone devote their life to hypersonic research if they did not think the work was more than simply intriguing but also important? And those with hands-on experience tend to be very forthcoming about the technical challenges. These are honest believers, but the funding realities tends to create enthusiasts rather than skeptics. There are a mere handful of people in the United States who have some scientific and technical understanding of hypersonic vehicles who are not working directly or indirectly for the military—and that means a very limited set of contrary views.

An early lack of naysayers almost always occurs when some new idea or proposed system first appears. A new idea gets pushed forward by enthusiasts and advocates and it takes a while for the analytical community to scratch its collective head and come back with: “Wait a second…”

A useful comparison here might be the so-called Revolution in Military Affairs concept: The idea that information technology was going to transform warfare. This paradigm was pushed initially by small groups of advocates who were certain they had something, well, revolutionary. It became almost a mantra at one point. But after a huge amount of research and discussion, the evidence  eventually showed that while new sensor and communication capabilities are clearly important, when both sides have those capabilities, it all balances out in a way that is somewhat short of a revolution.

In addition, unfortunately, the limited outside expertise in this specific case is just one example of the dramatic decline in independent scientific and technical talent focused on defense issues since the Cold War, when the big foundations made an explicit effort to maintain a cadre of talent that could ask hard questions about developments in military technology and weapons, especially nuclear weapons. That support remains vital but is at a much lower level these days. Moreover, many of the people whose expertise was honed by those programs during the Cold War are getting old (the author being but one creaky example).

Finally, this entire effort to develop hypersonic weapons is not really a lot of money—at least by Pentagon standards—so it remains largely below the radar of Congress and the public. Hypersonic weapons have gotten a free pass compared with the far deeper, more intense examinations that missile defense got immediately after President Reagan’s Strategic Defense Initiative, or Star Wars, announcement. But that was a program announced in a major speech by the president himself. Hypersonic weapons have not yet gotten anywhere near that level of attention.

So what questions should curious minds be asking about hypersonic weapons? Whenever anyone is trying to sell you any new gizmo and explaining how great it is, the first automatic, canned question should be, “Compared to what?” Yes, hypersonic missiles are fast, but not as fast as existing ballistic missiles. Yes, this is a new way to fulfill some proposed mission, but is there also some older (and probably cheaper) way to fulfill that same mission? (In this case, depressed trajectory ballistic missiles with maneuverable warheads can do almost everything claimed for hypersonic gliders.)

Many articles report, or exclaim, that there is no defense against hypersonic gliders. The word “unstoppable” pops up often. Again, compared to what? The United States cannot now defend against even modest ballistic missile attacks. One of Saudi Arabia’s most critical oil refining facilities was attacked by subsonic cruise missiles using decades-old technology that the Saudis, with a $180 billion defense budget, were not able to defend against at all. When headlines convey the message that the new thing about hypersonic gliders is that they are unstoppable, this implies that ballistic missiles are stoppable—that is, ballistic missile defense is easy, a done deal, and these new hypersonic weapons are undoing all that with revolutionary consequences. This is a major, dangerous distortion. Defending completely a huge area like the continental United States is an impossible task, whether against hypersonic weapons, ballistic missiles, or even subsonic cruise missiles. More limited point defense against intermediate-range ballistic missiles is extremely challenging but not impossible, but missile designers still have tricks that can make even that defense more difficult.

The next question should be “So what?” Almost every article mentions that hypersonic gliders are maneuverable, so their target points cannot be predicted. Well, the target point of a ballistic missile also can’t be predicted before it is launched 15 to 40 minutes before impact. So what? If the United States could predict where these weapons were headed—say, through the services of a psychic—what would it do with that information? In most cases, there is little it can do, whether the attack is from hypersonic gliders or ballistic missiles. One exception might be if the United States adopted a launch-under-attack doctrine for its intercontinental ballistic missiles (ICBMs); under that example, if commanders knew that the target points were ICBM silos, then they would allow launch, for fear of otherwise losing the missiles. If US doctrine is to ride out an attack on its nuclear-armed missiles, then knowing the target points would make no difference.

In practice, if the United States were under attack, all of its ICBMs could be on alert and could be launched on very short notice in just a couple of minutes—a warning time that launch crews could have even during a hypersonic glider attack because there isn’t much in ICBM country that is worth targeting other than ICBM silos.

Moreover, the number of incoming missiles might tell us almost as much as targeting might. The United States has about 400 ICBM launchers. If an enemy launched 50 hypersonic gliders, the United States would probably hold its ICBMs back regardless of where the gliders were headed. If an enemy launched 2000 gliders, the United States might well decide to launch its missiles, again regardless of where the gliders might be headed. Predicting target points can be useful in a few cases, but it does not make a lot of difference in most others.

Finally, analysts and journalists should ask questions about the motivations for this entire effort. The United States has a program, called Prompt Global Strike, with the aim of being able to hit targets on the ground pretty much anywhere in the world with a conventional warhead within about an hour. The concept first focused on missiles launched from submarines, but this created worries that the Russians and Chinese, seeing a US missile heading out, would have no idea whether it was nuclear or one of these new conventional Prompt Global Strike missiles. They might assume the worst, with dire consequences. Using hypersonic missiles instead, which are easily distinguished from ballistic missiles, was suggested as a solution to the nuclear-conventional ambiguity problem (although Russia and China would, of course, have no way to tell whether the hypersonic gliders were nuclear-armed or not).

This means that the beginning of the current surge in US interest in hypersonic gliders comes about because they could fill exactly the same mission that ballistic missiles would, admittedly, have been better at.

But Prompt Global Strike has by now been pretty much overshadowed, and it’s clear that much of the motivation for the US hypersonic weapons program is mainly a reflexive response to Russian and Chinese developments: If they do it, then we should too. US government officials have been quite explicit that the American effort is intended, in part, to avoid falling behind in this “race” with Russia and China. Yet, the strategic challenges of each country are radically different. Russian leaders have said explicitly that their hypersonic efforts are in response to US missile defenses and US abrogation of the Anti-Ballistic Missile Treaty, and they might be telling the truth. Of the three countries, the United States is, indeed, working hardest on ballistic missile defenses. When looking out at the threats in the world, Russia and China have very different views than does the United States. There is no reason for the United States to go on autopilot and mirror-image their moves with regard to hypersonic weapons.

Perhaps this whole idea will collapse under its own weight, but not before the United States has spent several billion dollars. That’s why the analytical community shouldn’t wait. It’s bad to be cynical but good to be skeptical. Those who write about this new weapon should stop and take a breath—and ask hard, honest questions.

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