Rethinking the hypersonic debate for relevancy in the Pacific

Lisa Porter and Michael Griffin served as the two top officials at the Pentagon’s Research and Engineering office from 2018-2020. In that role, they had a major hand in crafting the department’s hypersonic roadmap. In a new op-ed below, the two argue that the Defense Department needs to focus its investments on conventional long-range strike to ensure dominance in the Pacific. 

While the Russian invasion of Ukraine is currently occupying a significant amount of our attention, we must not lose sight of the escalating threat posed by the increasingly emboldened Chinese Communist Party (CCP). While we won’t recount here the long list of threatening, bullying behavior displayed by the CCP toward its neighbors in the Western Pacific, or the various publicly antagonistic declarations by President Xi Jinping toward the US and our Western values, such words and actions indisputably establish that Chinese leadership harbors menacing ambitions toward the US and our friends and allies, especially in the Western Pacific.

Given this concern, a sobering fact is that the ranges of interest in a Western Pacific conflict are substantially more demanding than what we faced in Europe during the Cold War. The distance from Berlin to St. Petersburg is about 825 miles, and to Moscow is approximately 1000 miles. In contrast, Taipei and the Taiwan Straight are more than 1,700 miles from Andersen AFB on Guam, while the 20 artificial islands in the Paracels and the seven in the Spratlys that have been built and fortified by the CCP since 2013 are over 2000 miles from Guam.

China’s “carrier killers,” the DF-21 ballistic maneuvering reentry vehicle (MaRV) and the newer DF-17 hypersonic glide vehicle, can reach Taipei and the Taiwan Strait in about twenty minutes from those island bases, while their “Guam killer,” the DF-26 ballistic MaRV, can reach Guam in under 25 minutes from the Chinese mainland.

Our own conventional strike options are currently far more limited. None of the deployed variants of Tomahawk have a range of more than 1,500 miles, and at that range require about three hours to reach the target. The new Maritime Strike Tomahawk will provide an effective range of about 1,700 miles when launched from an F-35C at its combat radius, with similar timelines. Something more is required. The United States will never initiate a conflict in the Western Pacific, but if the CCP does we must be able to respond far more promptly and with higher confidence than we can today.

What, then, should the US do to ensure that it can project timely conventional power over ranges relevant to the Western Pacific theater?

To answer this question, we need to take into account some important historical context. From 1987 to 2019, the US was bound by the Intermediate Range Nuclear Forces (INF) Treaty, which prohibited the development and deployment of land-based ballistic missiles having ranges between 500-5,500 km. While the treaty was with the then-Soviet Union and China was never a party to it, the US observed the treaty on a global basis, destroying the last of our 276 Pershing II ballistic/MaRV intermediate-range missiles by 1991.

Importantly, the INF Treaty had the effect of drawing a bright red line between “ballistic” and “hypersonic” missiles for US conventional strike strategy, because it permitted the development of missiles that flew substantially within the atmosphere. This exemption allowed the US to pursue the development of the Navy’s Conventional Prompt Strike (CPS) weapon and the Army’s Long Range Hypersonic Weapon (LRHW). While deployed from different launch platforms, these systems employ a Common Hypersonic Glide Body (CHGB), a common two-stage rocket booster, and have a demonstrated range of at least 1725 miles in tests.

In 2019, following years of Russian INF Treaty violations, the US withdrew from the treaty, but — critically — we did not then undertake a comprehensive review of what our conventional strike portfolio could and should be going forward. Instead, we continued to embrace a false choice between “ballistic” and “hypersonic” weapons, a narrative that persists today, where we find ourselves locked up in debates about whether ballistic missiles are superior to hypersonic missiles, how many hypersonic missiles we can afford, whether recent test failures should deter us from further development of hypersonic missiles, and so on. Such debates distract us from where we need to focus.

Any prompt long-range strike asset will necessarily be “hypersonic”; i.e., flying at Mach 5 or above. The terminology of the INF era, where we distinguished between “ballistic” missiles with largely exoatmospheric trajectories and “hypersonic” missiles flying substantially within the atmosphere, is now irrelevant. Regardless of the specific trajectory, all long-range prompt strike missiles appropriate for the Western Pacific theater will need to fly at Mach 17 or more, will need to deal with atmospheric reentry, should be able to employ MaRV, and will be capable of extreme accuracy.

We therefore think that the best way for the US to project timely conventional power in the Western Pacific theater is to invest in a long-range prompt strike portfolio consisting of a mix of weapons from ballistic, to ballistic with MaRV, to highly maneuverable hypersonic glide vehicles.

Noting that the booster parameters for CPS and LRHW are similar to that of the Pershing II, and that the CHGB is basically a scaled-down Pershing II MaRV, we further posit that a long-range, high speed, high accuracy, highly maneuverable conventional strike missile — call it a “Pershing III” — deployable from multiple platforms and locations with a tailorable trajectory depending on the intended target, could provide our warfighters with maximum agility and effectiveness in the Western Pacific.

Because any intermediate range conventional strike weapon could also carry a nuclear weapon (as several in the Chinese arsenal are designed to do), there is ambiguity about what an adversary might infer about its payload. How we address this ambiguity is ultimately a policy decision; our intent is to re-imagine the potential solutions available for conventional strike in the absence of the INF constraint.

Whatever we do, we must not let past strategies developed under different conditions for different adversaries and geographies constrain our approach to the Western Pacific theater. We contend that a flexible, robust, resilient conventional strike portfolio that can be affordably scaled to compelling numbers will be an effective deterrent against CCP aggression in the Western Pacific. Updated versions of the same old weapons platforms (e.g., carriers, tanks, bombers, and fighters) will not.

Lisa Porter and Michael Griffin were respectively the Deputy Under Secretary and the Under Secretary of Defense for Research and Engineering from 2018-20. The views expressed here are their own, and do not reflect those of the US Government or any other organization.