Laura Grego on China’s Hypersonic Missile Test

Dr. Laura Grego is a Stanton Nuclear Security Fellow at MIT’s Laboratory for Nuclear Security and Policy, on leave from the Union of Concerned Scientists’ Global Security Program, where she is senior scientist and research director. A physicist by training, she works at the intersection of science and policy on the topics of nuclear weapons, missile defense, and space security. She is a technical expert for The Woomera Manual on the International Law of Military Space Operations, an associate editor for the journal Science and Global Security, and a Fellow of the American Physical Society and a member of its Panel on Public Affairs. She has authored papers on topics from cosmology to nuclear security issues and has testified before U.S. Congress and the United Nations. Dr. Grego earned a PhD in experimental physics at the California Institute of Technology and a bachelor of science degree in physics and astronomy at the University of Michigan.

Grace Hickey CMC '22 interviewed Dr. Laura Grego on November 5, 2021.

Photograph and biography courtesy of Dr. Laura Grego.

The Financial Times reported in mid-October that China tested two hypersonic missile systems over the summer. China’s Foreign Ministry has rejected the report as false and claimed instead that China was testing reusable space technology. Do you believe that China was testing the hypersonic missile system? How does the lack of clarity around the event shape our perception of the US-China military rivalry and potential American response?

The Financial Times report described something that went into orbit and returned with a maneuvering glide vehicle, which could certainly be what the United States claimed: a nuclear-capable, hypersonic missile on a fractional orbital trajectory. But the description could also align with a reusable space plane or space shuttle technology. There are certainly more technical details that I would need to see in order to judge what it was, given that kind of description, and given that the United States Congress called it a new nuclear-capable hypersonic glide vehicle while China claimed it was reusable space technology. 

There are some tell-tale signs that could indicate quite a bit more about what the intent of the system was if you were able to observe the test. I do not have those details. 

In that respect, this test is similar to other types of tests that China has done in space that look like they could have dual use technology. These kinds of tests routinely get described by China as simply technology tests and in the U.S. as something menacing. You might even wonder, what kinds of things could China do that the US would not find menacing? I do not think there are many. 

Overall, I find it challenging to describe what the system is without more details, but both parties bring their own perceptions to the interpretation of the events.

How does the technology in the hypersonic missile set it apart from a ballistic missile? How does this impact the level of threat that it poses?

A ballistic missile is the typical technology associated with the delivery of nuclear weapons across intercontinental distances – these are called ICBMs. ICBMs are characterized by the launch of a large, powerful missile that burns for three to five minutes and releases its payload. The payload, a nuclear warhead in a protective re-entry vehicle, arcs up into space and comes back down under the influence of gravity. That journey takes around 30 to 40 minutes from China to the U.S. or the U.S. to China. Historically, ICBMs are always associated with nuclear weapons. They are the standard technology for swift delivery of munitions across intercontinental distances. 

A hypersonic boost-glide vehicle, which China is said to have tested, would not follow the same kind of path. Instead of the ICBM releasing the nuclear armed re-entry vehicle to go up into space and fall back to earth under the influence of gravity, the payload would instead be a glide vehicle that would use the speed from the missile to make itself go forward in the aerodynamic resistance of the atmosphere, which allows it to maneuver. So, instead of a predictable ballistic trajectory that is well defined, it is maneuverable and its path more difficult to predict. 

These hypersonic missiles are designed to go over long intercontinental distances from a less predictable trajectory. China has been developed and reportedly deployed a hypersonic boost-glide vehicle called DF-ZF in the United States, though it is not clear how it is related to what was tested here. 

The other technology that this test seems to demonstrate, or is claimed to have demonstrated, are FOBs, or fractional orbital bombardment systems. The orbital bombardment piece of that acronym means putting something into Earth orbit. When you put something into Earth orbit, it means that, with the right speed in the right direction, it will continue to go around and around every 90 minutes (in low earth orbits) until you deliberately bring it down. This is different from a ballistic missile, which comes up and goes down, but doesn't ever go into repeatable stationary orbit. 

If you put something into Earth Orbit, you can have it pass over your target from whichever direction you choose: it does not have to be the northerly direction that most ballistic missiles come from; it could come from the south instead. You would need not just a re-entry vehicle, you would also need to include a special deorbiting module with what you've launched to bring it back down when it gets in position to hit the target. Orbital bombardment is another strategy for evasive maneuver - it would potentially bring a nuclear weapon from a direction that the missile defenses are not anticipating. 

The fractional piece just means that the missile comes back down from orbit before it has completed one go-round. One reason that you would do that, rather than letting it go around a few times, is that the Outer Space Treaty, which is the fundamental law governing outer space, forbids the stationing of nuclear weapons in orbit.  Pretty much every country, and certainly all the space powers and the nuclear powers, are party to this treaty. There is a legal analysis which suggests that if you put the weapon into orbit, but you get it back down before it completes one entire orbit, it has not been stationed in orbit, an so it doesn’t contravene this provision of the Treat. 

It looks like China put something in orbit and brought it back down. That’s what you do in a FOBs strategy. However, putting something in orbit and bringing it back down is also exactly what you do for a space shuttle, or spaceplane. Of course you need to do this same thing to bring astronauts back home or carry back any kind of payload that you want to land. If you want it to land intact, you might use a space capsule or a parachute. If you want the landing to be as gentle as possible, you might have it land on a runway like the US Space Shuttle did, or the Pentagon’s X-37B space plane. If I knew more about China’s recent test, and knew it landed on a runway or was trying to land on a runway, that would indicate to me that it was more of a space plane and something bringing human beings or precious cargo back to the earth. 

But if it crash-landed, that is different. A nuclear weapon does not need a beautiful runway landing, a nuclear weapon just needs to get to where it’s going. This is an example of some technical details that would help us sort this out. 

Overall, the story is getting something long distances, using different technologies. Hypersonic missiles might do the same job as ballistic missiles but with a different path.

One difference is that ballistic missiles are decades-old very well-developed technology: once you build them, they are quite reliable. Alternatively, hypersonic missiles can be quite challenging from an engineering point of view. They are more complex and harder to build reliably. One motivation for developing this more difficult technology is that these maneuvering crafts can be harder to intercept with existing missile defenses, which have been built for ballistic missiles, not maneuvering missiles. They are a way to evade the kinds of defenses the U.S. has fielded, or other countries may field in the future.

Various sources have reported that U.S. officials were “surprised” by how quickly China was able to develop this hypersonic missile. Why do you believe that China’s test of this new technology was unexpected?

I can't imagine that it was actually unexpected. China has declared that it is building these missiles, and it has published its research information in open-source journals. China seems to be very proud of this technology. 

There may have been some surprise that hypersonic glider technology was tested using the method of putting it in orbit and then returning it from orbit, though that should not really be a surprise either.  China is a very active space power. Of course it can do those things. 

It is also possible that through the game of telephone someone who was impressed with a piece of the engineering in the test talked to someone else who interpreted that as a great surprise. However, China is technologically sophisticated, it is a space power, and it has been developing hypersonic glide vehicles. So, anyone who has been following what China has been doing would not see this test as wholly unexpected. 

How will the U.S. respond in terms of the development of its own arsenal? Can and should the U.S. begin to develop its own hypersonic missile stockpile?  

The United States previously spent around $5 billion in today’s dollars in the 1960s pursuing a hypersonic glide vehicle in a program that was called DYNA-SOAR. The program was then set aside when the U.S. realized there was not really any mission it was well suited to. Ballistic missiles did the job well enough.

The United States returned to this idea of hypersonic missiles in the early 2000s. However, the goal then was to find a way to hit time-sensitive, far-away targets with conventional, meaning non-nuclear, weapons using a technology that would make them easy to tell apart from nuclear weapons. As we just talked about, the way countries currently target long distances very quickly is with intercontinental ballistic missiles, but because those are so closely associated with nuclear weapons, you would not want to use them in some other way, because they might be interpreted as a nuclear weapon. Therefore, there was an interest in using these glide vehicles to go these long distances rapidly in a way that could be discerned from nuclear weapons. That is no longer the primary mission for the United States hypersonic missile program.

Instead, the United States research program is refocused on shorter-range glide vehicles to use in the theater of war. Like the missiles that were being worked on in the early 2000s, these are also only for conventional weapons. The difference is that they are not for intercontinental ranges. Right now, the U.S. is not pursuing intercontinental range glide vehicles, or at least that is not its primary interest.

Thus, the U.S. interest in hypersonic missiles is different from China and Russia’s interest in pursuing them. While all the countries are in a race to continue to develop the technology, they have different reasons and different goals. There's really no reason to for the US to try to build a hypersonic glide vehicle for intercontinental distances. Ballistic missiles work for those purposes. Getting around U.S. missile defense system is one of the core drivers for Russia and China to pursue maneuvering hypersonic missiles, but the U.S. doesn't face the same challenge. Neither Russia nor China have substantial missile defenses that the US needs to get through or around. It is not analogous.

However, the United States is already planning to build a defense against these maneuvering hypersonic missiles. So ballistic missile defenses beget maneuvering missiles to get around them, which in turn drives building a defense against these new missiles. It’s a pretty classic arms race dynamic.

What is driving China to develop this new technology? 

There are technical and organizational drivers for China. First, there are almost always internal bureaucratic reasons that a project gets started and continues. Second, the United States thought this was an important technology, pursued it in the past, and returned to it again in the early 2000s. China would not want to be left behind and thus it makes sense that China would want to understand this technology and master it. 

As for strategic drivers, a primary one, as we talked about, is the goal to evade U.S. strategic missile defenses. Of course, China has other strategic relationships that it needs to manage, but if we're just looking at the U.S. and China, the United States has a much larger nuclear arsenal. It has invested tens of billions of dollars and many decades of effort in building defenses against ICBMs, and the U.S. is also pursuing these conventional prompt strike capabilities, which China fears that it may use to target China’s command-and-control structures. If you take all these factors together—the large U.S. nuclear arsenal, its advancing intelligence, reconnaissance and targeting capabilities, its conventional weapons, and its missile defenses—China could think that the United States may eventually believe it could strike China first and not risk retaliation.

One of the strategies that China uses to make sure the United States does not ever get to that point is to build systems that can get around U.S. missile defenses. As we talked about before, these hypersonic glide vehicles are evasive, and they will come from a different direction than ballistic missiles do. U.S. missile defenses are really only optimized for ballistic missiles. 

You wrote in the Financial Times that you believe that serious diplomatic intervention is the only way to quell the arms race between the United States and China. What are the obstacles to a productive bilateral engagement on this critical issue?  What could be the consequences of a full-fledged nuclear arms race?

We are now experiencing a similar offense-defense dynamic between the U.S. and China as during the Cold War between the U.S. and the Soviet Union, when there were concerns that defenses could interrupt mutually assured destruction. For example, the Soviet FOBs strategy was designed to counter U.S. missile defenses. The Soviet Union abandoned the FOBs strategy when the U.S. abandoned those missile defenses. 

There was certainly an offense-defense dynamic that helped drive the nuclear arms build-up in those years. The Anti-Ballistic Missile Treaty of 1972 was designed to quell that dynamic. That treaty limited the defenses that each of the two countries could field. That treaty was a cornerstone of the following nuclear arms reductions treaties over the next decades. 

The U.S. and Russia are no longer bound by that treaty: the U.S. exited in 2002, and that restriction on missile defenses no longer exists. You now see this dynamic happening again, because the U.S. is fielding defenses, and Russia and China have new systems they are building that either evade, penetrate, or interrupt missile defenses. Then, the U.S. sees those systems and reacts to them. For example, this system that China tested was seen by some people not as a fairly predictable reaction to defenses, but as a new thing that needs to be addressed and countered. This thinking could create a spiral in which each move by one country generates a counter-move by the other. Without recognizing that, and without stopping to think, we can easily repeat the offense-defense dynamic. 

Right now, all three countries, the United States, Russia, and China, are investing enormous amounts of money to modernize their nuclear arsenals. China appears to be not just making its arsenal more sophisticated, but larger. This is dismaying because China has long taken a fairly moderate stance and had a relatively small nuclear arsenal. 

What are the ways that we can make sure we do not keep going in that unhelpful offense-defense direction? I personally do not think that human beings and nuclear weapons can coexist indefinitely; we will need to deal with them. We will need to figure out how to walk them back, make fewer of them, and reduce those risks.

The U.S. and Russia are starting to hold talks that are in support of an eventual arms control discussion, but China has not been interested in joining. There was a big push by the previous president that the United States would not extend New START, the current nuclear arms limiting treaty, unless we had a commitment for China to engage in arms control negotiations. China, of course, has a much smaller arsenal, and claimed not to see the need until the U.S. and Russia had arsenals that were much closer in size to China’s. However, there may be some interest in talking about how other types of emerging technologies might be affecting each other's security. We will need to start talking about the technology that China reportedly tested, and other new emerging technologies, sooner rather than later. Beyond just the technologies we talked about today, there are other weapons that are being developed to be deployed in space, and other precision conventional weapons that countries are concerned about. We need to have conversations about these. 

The United States and the Soviet Union, and then Russia, had a lot of experience with each other over the course of negotiating and monitoring the compliance of the treaties that they concluded over the years. But the United States does not have the same experience with China. We have not sat and hammered out a treaty with the Chinese, and so have not figured out what each country’s true security concerns are and what they might give up in order to get other benefits. Even the personal relationships that are developed between governmental and military officials that happen in the course of these types of negotiations are important stabilizing factors. We do not have the same level of relationships with China as with Russia. 

Many are skeptical that any type of arms control treaty with China is realistic anytime on the horizon, and I share that skepticism. However, the process of engaging each other in these types of discussions and negotiations is still important. Then, when the time is right, we have all the relationships in place and the conversations have been started. 


Grace Hickey CMC '22Student Journalist

Mike1979 Russia, CC BY-SA 4.0 <>, via Wikimedia Commons

Share this:

Leave a Reply

Your email address will not be published. Required fields are marked *