TAMPA, Fla. — The U.S. military is pouring money into hypersonic research, and it’s making China and Russia —which have their own similar programs — nervous. But the accelerating effort to build missiles that fly at speeds between Mach 5 to Mach 19 is also alarming some in the nonproliferation community. Despite Pentagon officials’ assurances that superfast weapons will carry only conventional warheads, some believe that other nations may well treat any hypersonic launch as a potential nuclear strike.

It’s been a good year for hypersonic researchers, who got a 50 percent bump in the Defense Department’s 2017 budget request. The Air Force plans to test a hypersonic missile by the end of the decade.

The Pentagon, whose long record of hypersonic research stretches from the X-15 rocket plane to the Boeing X-51 scramjet and beyond, is today funding the Lockheed Martin Falcon Hypersonic Technology Vehicle 2 program, the Raytheon Hypersonic Air-breathing Weapon Concept (HAWC), and the Raytheon/Lockheed Tactical Boost Glide. The Defense Advanced Projects Research Agency gave Raytheon $20 million and Lockheed $24 million for the latter.

Raytheon is pouring tens of millions of its own dollars into hypersonic research.

“These are very specific point design weapon systems. We have picked design points where the technology is available today and we can put these things together as systems now,” said Thomas Bussing, vice president of Raytheon’s Advanced Missile Systems. He added that 3D printing and additive manufacturing have reduced the complexity of hypersonic devices. “Not only can you build them, you can build them affordably.”

The company is working on two kinds of hypersonic missiles. One is a boost glide system that rides a rocket into space, then reenters the atmosphere and glides to its target at up to 14,000 miles per hour. The other is an airbreathing missile, a close cousin to the ramjet, that scoops up oxygen as it flies a flatter, Mach-10 path to its destination.

The primary challenges in the boost glide system were “materials, stability control, the aerodynamics of the vehicle itself,” according to Bussing. In the air-breathing missile, “it’s all about the engine and having the engine operate over a range of conditions.”

Unlike the ballistic path followed by an ICBM plummeting toward its target, a cruise missile can steer its way past defenses, or, in some cases, sneak in below radar coverage. Being able to strike so quickly has distinct advantages, if you’re trying to penetrate sophisticated air defenses.

Interest abounds; the Navy is considering arming its ships with a tactical boost glide weapon, said Joe Doychak, the associate director of aerospace technology for the assistant defense secretary for research and engineering.

What do you do with a rocket that can travel that fast over intercontinental distances? A 2014 RAND report noted hypersonic technologies “could be used in future nuclear-armed systems.” The Pentagon could—if it chose to—turn hypersonics into an entirely new type of nuclear weapon.

“At this point, our hypersonics program is really a technology development program, purely focused on conventional” payloads, said Stephen Welby, assistant defense secretary for research and engineering. “There’s nothing in the budget” related to modeling, researching, or exploring nuclear-armed hypersonics.

While the U.S. is also planning to spend more on modernizing U.S. ICBMs, the “two things are uncoupled” Welby said Wednesday at a National Defense Industrial Association, or NDIA, event here.

Asked about potential payloads, a Raytheon spokesman said only that “the hypersonics programs on which Raytheon is currently a performer are focused on advancing the technologies that support hypersonic flight. The eventual application of those technologies in support of a customer mission is for the customer [the U.S. government] to answer.”

Superfast Strike Jet

The ultimate goal of today’s hypersonic research, military leaders say, isn’t a nuclear missile but a re-usable hypersonic jet.

“We see this as being a long-range program,” David Walker, the U.S. Air Force deputy assistant secretary for science, technology and engineering said at the NDIA event. “It’s 2020 for the missile, 2030 … until you get into something that’s refurbishable” [meaning an aircraft you could potentially use again] and probably 2040 until you get into something that’s a totally reusable type of capability.”

In his presentation, Walker laid out the Air Force hypersonics roadmap. It starts with a quick-firing tactical strike missile, ready around 2020. Around 2030, it foresees an ISR craft capable of “deep strike of high value targets.” And finally, a “re-usable and persistent” ISR and strike craft labeled “tech ready by 2040.”

The military sees hypersonic airplanes as one answer to the rise of more capable programmable radar. “Our ability to operate in a stealthy mode is starting to lose its advantage because of the advanced radars,” Dick Urban of the Defense Advanced Research Projects Agency, or DARPA, told the crowd at NDIA. “We think that speed is going to give us that extra advantage.” (Welby called advanced programmable radars “a challenge” but said that they did not necessarily make stealth obsolete.)

But that doesn’t mean that hypersonics are invisible. They’ll have a bright infrared signature visible from space.

Inherently Destabilizing?

The same speed advantage has alarmed members of the non-proliferation community, who believe hypersonics raise the risk of nuclear conflict.

“I see hypersonics as weapons whose only plausibly logical use would be a niche role in a strategic first strike vs. Russia or China. So the nuclear standoff already exists, and this road is taking us closer to war,” physicist Mark Gubrud said by email. (He also says the speed advantage of hypersonics is overstated; ICBMs are still faster.)

An enemy would have no way to know whether or not such a missile was carrying a conventional or nuclear warhead.

“If I see a cruise missile flying over, I have to assume it’s nuclear,” William Perry, a former defense secretary, said at a recent event in Washington.

He is not unique in that concern. Tong Zhao, an associate in the Carnegie Endowment’s Nuclear Policy Program, echoed this concern in a June essay for the Bulletin for Atomic Scientists. “Some analysts in China suspect that the United States is seeking the ability to eliminate Beijing's nuclear deterrent in a first strike—and if Washington successfully develops hypersonic missiles, Beijing’s confidence in the credibility of its nuclear deterrent would only erode,” Zhao wrote. “Already, some in China are discussing whether Beijing should, in the face of new conventional threats to its nuclear arsenal, alter its unconditional no-first-use policy.”

China is also working to develop hypersonic cruise missiles and has already conducted six tests of a hypersonic weapon, the WU-14. Russia and India are also planning to test a hypersonic missile called the BrahMos-II capable of reaching Mach 7, in 2017.

In the same series of essays for the Bulletin, Gubrud called for banning even tests of hypersonic weapons, arguing that such a prohibition “stands out as an easy and highly significant opportunity to resist an onslaught of destabilizing weapons technology.”

The history of U.S. advances in hypersonics is intertwined with nuclear weapons research, Gubrud points out. “The US has tested maneuvering reentry vehicles which were intended for nuclear delivery. The Advanced Hypersonic Weapon, successfully tested in 2011, was derived from the Sandia SWERVE [Sandia Winged Energetic Reentry Vehicle Experiment] maneuvering reentry vehicle, which was intended as a nuclear warhead,” he told Defense One.

“The US may not be planning to use hypersonics for nuclear delivery, but US statements allege that Russia and China do intend to do so, and the technical possibility is clear,” he says. “More importantly, even non-nuclear hypersonic weapons would be mainly intended to attack strategic targets including nuclear weapons and the infrastructure of nuclear war. The best way to prevent this needless uptick in the nuclear arms race would be to initiate a moratorium on hypersonic missile testing (both glide vehicles and cruise missiles) and challenge Russia and China to reciprocate and to negotiate a permanent ban.”

The unique advantages that the Pentagon sees in hypersonic technologies suggest that is unlikely to happen.