Some keys to understanding the Technology, its Operation and Significance...
By CAPT Jérôme Henry, Executive officer of air defense FREMM Frigate Lorraine
and RADM Emmanuel Slaars, French Joint Force Commander in Indian Ocean
The First Libyan Civil War had ended in October 2011 with the overthrow of Colonel Gaddafi’s government. At that time, most countries were focused on terrorism and the fight against asymmetric threats. Yet just a few months later, on April 4, 2012, the French anti-air defense destroyer Forbin was off the Île du Levant in the Mediterranean, preparing to accomplish a seemingly anachronistic feat: intercepting a target designed by the US Navy to reproduce the behavior of the Russian KH31 or SSN-22 supersonic anti-ship missiles. These missiles, built in the late 1980s, were intended to counter US Navy carrier battle groups. In this test, the French Navy sought to validate for the first time the performance of the Franco-British-Italian PAAMS (Principal Anti-Air Missile System), firing an Aster missile, in a live-fire test. The success of this test showed that France had entered the exclusive club of navies capable of defending against supersonic anti-ship threats.
The United States, at the same time, was taking advantage of the slowdown in Russian missile innovations, by taking the lead in both hypersonic missile defense (anti-ballistic missile systems like SM-3 and THAAD), and offense, notably the Prompt Global Strike project initiated in the early 2000s. This will allow Washington to be able to conduct a conventional strike anywhere on the globe in less than an hour, for example to neutralize mobile offensive land systems even when defended by robust air and missile defense systems.
The return of Great Power Competition between nation-states, and the disruption of the rules-based international order, has revived the interest of the great powers in the development of these weapons. Beijing would thus consider that American developments of hypersonic missiles would make it possible to conduct preemptive conventional strikes against the Chinese nuclear arsenal and the associated infrastructure. China is therefore striving to develop the means of carrying out retaliatory strikes, while maintaining strategic ambiguity as to whether the warheads would be conventional or nuclear. For Russia, it is likely that the recent resumption of efforts (e.g., the Avangard hypersonic glider) responds to the deployment of American anti-missile systems in the US at home and overseas as well as in Europe as Vladimir Putin underlined during his speech on March 1, 2018. This results in a weakening of the European treaties supposed to fight against the proliferation of such systems, including in particular the Missile Technology Control Regime (MTCR) and the Hague Code of Conduct.
The Missile Technology Control Regime (MTCR) is an informal grouping of countries that seek to limit the proliferation of missiles and their technology. The MTCR aims to limit the risks of proliferation of weapons of mass destruction by exercising control over the export of goods and technologies likely to contribute to the manufacture of such weapons. Initially focused on missiles and unmanned aerial vehicles capable of carrying a payload of at least 500 kg over a distance of at least 300 km, it is now extended to technologies related to this capability. Founded in 1987 by the G7 countries, it currently comprises 35 members who are expected to act responsibly and prudently with respect to the export of a list of sensitive technologies. Russia is party to this regime and organized a plenary session in October 2021. China, Iran, Syria or North Korea in particular are not.
The Hague Code of Conduct is the only instrument with a universal remit to combat the proliferation of ballistic missiles capable of carrying weapons of mass destruction. Resulting from a French initiative, it is now signed by 143 nations. Operating on a voluntary basis, it contributes to strengthening security, international and regional stability through transparency measures in terms of space and ballistic activities. Its presidency rotates and it is notably the subject of a bi-annual resolution of the United Nations General Assembly.
The old arms race has been relaunched with new hypersonic weapons more capable to penetrate air defense systems, including Western ones. This arms race is very much an assertion of power by nation-states through the demonstration of advanced, lethal technologies. It is in this context that hypersonic weapons, which had begun development at the end of the Cold War, are getting a new lease on life in this era of Great Power Competition. Russians and Americans both offer new capabilities in the form of Hypersonic Glide Vehicles (HGVs) and ramjet Hypersonic Cruise Missile (HCMs). Are these hypervelocity weapons, which have both the attention of media and lawmakers, in the process of revolutionizing air warfare? Or do they only constitute a new stage in the evolution of armaments, like that of supersonic missiles in the 1970s? And what, specifically, are the consequences for the French Navy of hypersonic missiles?
Technological state of the art
The commonly accepted definition of a hypersonic missile is that it is capable of moving at more than five times the speed of sound while also being able to maneuver – in other words, it does not fly solely on a ballistic trajectory. Ballistic missiles, such as intercontinental ballistic missiles (ICBMs), are a well-understood technology; while their initial speed can exceed Mach 20 during part of its flight (almost 7 km per second), they cannot significantly change their flight path once in terminal phase. Hypersonic missiles, by contrast, are able to significantly change their direction during their flight, up through the terminal phase, allowing them to evade defenses and improve accuracy upon approach to the target. In this range of weapons, it is possible to distinguish three types of technologies.
The first type of technology consists of ballistic missiles with maneuvering warheads. These weapons are based on technologies put into service during the Cold War to correct or change the trajectory of the weapon at the end of its course. The so-called MaRV (Manoeuvrable Reentry Vehicle) technologies allow the evolution of ICBMs or intermediate-range ballistic missile like the Pershing II (contemporary with the SS-20 crisis in Europe in the 1970s and 1980s). The challenge of the terminal maneuver is either to obtain a trajectory that is more difficult to predict (intercontinental missile) or to adjust the impact zone (Pershing II). The use of nuclear warheads makes it possible to limit the need for precise trajectories. These technologies have now progressed enough to allow the reentry vehicle to either (a) rebound at the end of the inertial trajectory, in order to increase the range, or (b) to enter the atmosphere in such a way as to suddenly degrade the kinetic energy of the vehicle and reducing the speed so as to allow terminal maneuvers based on more significant corrections. The downside of this maneuver is that the missile must travel significantly below Mach 20 in its terminal phase.
The second type of technology is called the supersonic combustion ramjet or scramjet, which maintains continuous thrust in the atmosphere throughout the duration of the flight. Unlike the conventional ramjet, in which the air enters the combustion chamber at a subsonic speed, scramjets have a supersonic compression air inlet. Unlike with ramjets, the missile must first be accelerated to supersonic speed in order to ignite the scramjet. In addition, since the scramjet combustion chamber is optimized for a specific flight profile, this weapon will favor a fixed altitude during the majority of the trajectory.
The third technology involves launching a glider from a ballistic missile during its ascending phase, then piloting this device to “bounce” off the layers of the atmosphere to extend its range and change direction. This gives it a trajectory that is very complex to predict, but also leads to very high mechanical and thermal stresses on the terminal vehicle. Its range and final speed will depend on the initial thrust and then the profile of its kinetic energy degradation as it bounces off the layers of the atmosphere. As with the MaRV, the terminal velocity of the glider will be greatly reduced from the initial Mach 20, even potentially below Mach 5.
Advantages of hypersonic missiles
The added value of these hyper-velocity weapons resides above all in their extremely high cruising speed, which reduces the reaction time available for an anti-aircraft defense system, even for integrated air defense (IADS) systems that combine detection, analysis, decision and interception. Reducing the time of flight of the attacking weapon decreases the reaction time of the defender. The defender, in other words, has a much-compressed OODA (Observe, Orient, Decide, Act) loop in order to react to the threat. This is the challenge of the cooperative engagement capability  that aims compress the OODA loop. In the case of hypersonic gliders, in addition to their speed, they do not follow a hyperbolic ballistic trajectory after their release, flying essentially “under the radar” for much of the flight, also reducing the reaction time of the defender.
Beyond the reaction time, maneuvering at hypersonic speeds generates considerable constraints. However, for each “g” of acceleration of an offensive maneuver, the defense (interceptor) missile must develop several “gs” to correct its trajectory. Consequently, intercepting a hypersonic missile requires extremely maneuverable missiles and sufficiently efficient guidance algorithms to predict the trajectory of their target with high warning and high precision.
In addition, the final trajectories of these weapons are only predictable at a late stage, which makes the calculation of the point of interception very complex, unlike for intercepting a ballistic missile. On the other hand, an intercontinental ballistic missile degrades its energy little during flight, which allows it to maintain speeds greater than Mach 20, with multiple reentry bodies (including decoys) that are complex to detect and classify, conferring a lethality that belies the straightforward nature of predicting a hyperbolic course track.
Russia is probably the most experienced operator of hypervelocity weapons, with three flagship systems. The first is the AVANGARD, an intercontinental hypersonic glider that is powered in its initial phase by the ICBM UR-100N UTTKh (SS-19 Mod 4 ‘Stiletto’), said to be in service since 2019. It would be capable of carrying nuclear weapons and would maneuver at Mach-20+ at an altitude of 100 km. The second hypersonic missile is the Kh-47 Kinzhal, an aero-ballistic missile fired from aircraft, which has maneuvering capabilities. Operational since 2018 according to Russian officials, it would reach Mach-10 in the terminal phase, dropped from MiG-31K or Tu-22M3 heavy bombers. It has allegedly been used during the conflict in Ukraine for the first time on March 19th and deployed two times since then. A version with reduced dimensions, embarked on the Su-57 fighter, appears to be in development. Finally, the most publicized hypersonic missile remains the 3M22 Zircon (Tsirkon) scramjet missile, which would reach Mach 8 and have a range of 500 to 1,000 km. Trial launches from surface ships and submarines were carried out in 2020 and 2021, with entry into service projected in 2022.
On the Chinese side, the oldest armaments are the ballistic missiles with maneuvering warheads (DF-21 and DF-26) credited with ranges ranging from 1,500 to 3,000 km, with a hypersonic terminal velocity and which would have the capacity to correct their final trajectory to hit moving targets. As famous as the Zircon, these missiles were first known as the “Guam killers”. Now displaying hypothetical anti-ship capabilities, they are today presented as “carrier killers”. The DF-26 could conduct precision conventional or nuclear strikes against ground targets, including US bases in the Marianas. Chinese illustrations published in November 2019 suggest that the H-6N strategic bomber could carry the DF-21D. The embarkment of DF-26s on future Chinese destroyers is also envisaged. China also has a glider, the DF-17, officially unveiled on the National Day (70th anniversary of the creation of the People’s Republic of China) in October 2019. This missile would be composed of a DF-ZF glider powered by a booster ballistic missile. Its announced range of 1,700 km would be combined with a speed of Mach 5. As with the DF-21D, the carriage of this missile by H-6N strategic bombers is mentioned. Finally, China may have tested an intercontinental glider in August 2021, which the Chair of the JCS General Mike Milley called a “Sputnik moment”, meaning a strategic surprise for the American armed forces.
On the American side, the DoD has five major programs and two hypersonic technological demonstrators, although none has been declared officially operational to date. In the field of gliders, the US Army is developing the LRHW (Long Range Hypersonic Weapon) using a Common Hypersonic Glide Body (C-HGV) in partnership with the US Navy. The Navy continues the CPS (Conventional Prompt Strike) program resulting from the Prompt Global Strike initiated by President George W. Bush. It aims to develop an HGV capability onboard the three Zumwalt-class cruisers and the new Virginia-class Block V attack submarines. American doctrine does not provide for the development of hypersonic weapons carrying nuclear warheads; the flight profile of gliders are intended to be sufficiently different from that of a ballistic missile to avoid a miscalculation. The Air Force is developing its own glider, the ARRW (Air-launched Rapid Response Weapon, AGM-183A) launched from B-52 bombers or even B-1s. After three failure, May 14, the USAF confirmed a successful flight test of the missile launched from a B-52H. The announced date for the operational use of these weapons is 2025. The American armed forces are also developing ramjet HCM missiles: the HACM (Hypersonic Attack Cruise Missile); the HAWC (Hypersonic Air-breathing Weapons Concept) demonstrator (last successful test flight in March); and the sea-based Hypersonic Air-Launched Offensive (HALO), designed for carrier-based F’A-18 Super Hornet fighters that operate from aircraft carriers. If the American projects do not seem as far along as those of the Chinese or the Russians, the research in the field actually dates back over two decades, to the aforementioned Prompt Global Strike initiative in early 2000s. The delays in bringing these weapons from research into service can be explained by the many technological challenges that these programs must face and the high reliability expected, in accordance with occidental standards.
Limitations of hypersonic weapons – speed
Operating in the hypersonic domain presents technological complexities that for decades have been addressed during the development of intercontinental ballistic missiles, which as noted, exceed Mach 20 in much of their flight. First of all, atmospheric friction heats the missiles to several thousand degrees Celsius. The warhead of an ICBM is protected by an ablative coating, and it only spends a short period of time plunging through the atmosphere, which means that both heating and loss of speed are reduced. By contrast, a hypersonic glider experiences high thermal stress throughout the glide phase, which is concentrated on the lower and front faces of the glider. This necessitates a high level of research and development of appropriate heat shield materials and manufacturing . In addition, the gilder must maintain proper orientation to manage thermal stress, and this introduces additional complexities in terms of control surface design, thrust vector control and displacement of the center of gravity of the missile.
Hypersonic maneuvers or “bounces” generate high g-force accelerations which dictates very strict requirements for navigation systems, in particular inertial ones. Furthermore, while the ionization of the air around a hypersonic body has little impact on its detection by terrestrial or maritime radars, it can severely limit radio communications (as witnessed by the re-entry of Apollo spacecraft and the Space Shuttle), which proves problematic for external guidance using data link or even GPS. Finally, in the case of an HCM, the operation of a scramjet entails flight constraints in altitude and in profile, because the combustion chamber is optimized for temperature and air pressure conditions corresponding to a specific altitude. In general, very high altitudes are chosen (greater than 50,000 feet). If tactics dictate the need to vary the altitude of the missile, this can only be done at the cost of “deoptimization” of fuel consumption and therefore range, which can be reduced by as much as 80 percent from the theoretical optimum.
Limitations of hypersonic weapons – targeting
Hypersonic missiles have so far been used (for example, the alleged Kinjal strikes in Ukraine) against stationary sites. If it is a question of hitting a moving target like a ship, we must add to the constraints above the problems of targeting and terminal guidance. For this type of target, the challenges related to the transmission and real-time refresh of information on a moving target still seem far from resolved. Another solution would be use a seeker. The problem with placing a seeker on the missile is that it must be located at the nose, which as noted is subject to the highest thermal stresses. In the present case, the use of a heat shield seems incompatible with that of a seeker positioned just behind, which must either emit and receive electromagnetic waves in return, or possibly work in the visual or infrared fields, which reduces its range or exposes it to the thermal phenomena already discussed at length. There are solutions for jettisonable fairings in the dense layers of the atmosphere to protect the seeker, but this jettison must be carried out once the missile has left the hypersonic range to avoid high g-force stress on the missile airframe.
Beyond the thermal constraints, remains the question of targeting to correct the trajectory of the missile. The speed of these weapons implies unmasking at very long distances compared to subsonic missiles. In addition, if the hypersonic missile flies at very high altitude, it must solve radar discrimination problems in what is commonly called sea clutter and therefore must use radar imaging processes using SAR (Synthetic Aperture Radar) technologies. Added to this is the identification of the target, which must be based on powerful algorithms. All these elements mean that in order to target a naval vessel, the missile must slow down and leave the hypersonic domain in the final phase, returning to “normal” supersonic speeds. However, a maneuvering supersonic missile remains a very complex target to intercept, especially if a substantial part of its flight was made at hypersonic speeds, reducing the time available for the OODA loop.
Defense against hypersonic weapons
The interception of hypersonic missiles presents several challenges. The detection of the launch of the missile relies on relatively mature technologies. For several years, the French Navy’s air defense vessels have been connected to NATO’s SEW (Shared Early Warning) alert network, the detection of which is based on space sensors in the infrared band. Hypersonic missiles operate at speeds normally filtered out by radar systems in order to limit false targets, which needs to be accounted for. Guidance for intercept will require very precise tracking to calculate the correct aim point. Defensive missiles themselves must be highly maneuverable to reach aim point accurately in time and position. The US Navy has said that it has risen to these challenges with the combination of the SPY-6 radar system and the SM-6 interceptor missile. During Flight Test Experimental – 01, in March 2020, an Aegis destroyer simulated an HGV interception with a SM-6 Dual-II missile. The U.S. Missile Defense Agency (MDA), in cooperation with the US Navy, conducted Flight Test Aegis Weapon System 31 Event 1 on 29 May 2021, of the SM-6 against a medium range ballistic missile. However, even with a salvo of two missiles, no intercept in terminal phase was achieved. The US Navy and the MDA are also embarked on a program to intercept HGVs further upstream in the glide phase (Glide Phase Interceptor or GPI initiative) , therefore further upstream. This implies having sufficiently advanced tracking and guidance systems to enable an SM-6, with an enhanced propulsion system , to reach its target in the hypersonic maneuvering range. The US Navy is therefore organizing to adapt its means to counter this new threat, in a similar manner to its development of capabilities against the KH31 anti-ship missile, using the SM-2 and GQM-163 Coyote supersonic target.
On the European side, the response to hypersonic missiles is beginning to be structured, and the Twister project (Timely Warning and Interception with Space-based Theater surveillance) carried out by France within the framework of European Permanent Structured Cooperation could be one of the first developments to benefit concretely from the support of the recent (2021-2027) European Defense Fund. In this regard, it is desirable that the research and technology effort follow a distribution based on the so called logic of the best athlete for Twister’s most complex sets.
Twister: Timely Warning and Interception with Space-based TheatER surveillance
Adapted to the reality of offensive missiles in 2035 and beyond, the future Twister program aims to strengthen Europeans’ ability to better detect, track and counter hypervelocity missiles, in close collaboration with NATO, via a combination of solutions based on advanced space warning and endo-atmospheric interceptors. The early warning component, called the eye of Odin, notably associates Thales Alenia Space with other manufacturers from the Member States involved. It should be based in particular on the use of a constellation of satellites, the technology of which will be the subject of future upstream study work, to meet both alert and tracking needs. As for the interceptors, baptized European Air & Ballistic Missile Defense Interceptor, they would capitalize in particular on the successful architecture of the MBDA Aster interceptor, integrated into a set of two and perhaps three propulsion stages.
The study work associated with this program on which several European Member States are already working receives financial support from the European Defense Fund over the period 2021-2027. In the naval field, this future system, and in particular this new generation of endo-atmospheric interceptor, would be compatible from time to time with the future generation of French Navy air defense frigate, whose primary mission should remain the protection of a carrier battle group. in a contested environment.
Consequences for the French Navy
In 2012 and again in 2021, the French Navy in turn demonstrated its ability to intercept a KH31 range anti-ship missile, using its Aster system against supersonic targets. It must now renew this type of demonstration in the face of these new threats. To do this, it has the project management capacity of the Directorate General of Armaments (DGA), the French military research, development and acquisition agency, coupled with significant European industrial assets. The missile manufacturer MBDA in particular has proven skills in the field of scramjets, such as the planned ASN4G nuclear-armed hypersonic cruise missile program. In addition, to replace the Exocet, famous but of respectable age, the joint French-British program Future Cruise/Anti-Ship Weapon will operate at high supersonic speeds, which makes it possible to understand the constraints of this type of flight against moving targets. For several decades, France has excelled in using the combination of speed plus maneuverability pair to break through enemy defenses, notably the ASMPA nuclear supersonic cruise missile. In addition, thanks to its commitment to the Strategic Oceanic Force and the development of ICBMs, the Ariane Group has expertise in the field of hypersonic flights and materials associated with thermal constraints. This industrial group is also responsible for the VMaX hypersonic glider technology demonstrator.
Nevertheless, given the investment of the major powers in the field of hypersonics, and the rate at which they are evolving, it remains necessary for the French Navy to deepen its knowledge in this field, alongside the DGA. A number of unknowns still remain around the operation of these weapon systems: their guidance, their ability to maneuver, the appropriate materials and technologies, and of course the limits of their speed. Tests and development are still necessary to better understand the functioning of these systems in order to better identify their weaknesses and exploit their flaws.
In terms of defense against enemy hypersonic missiles, the complexity of engaging a moving target seems to offer opportunities for a final phase interception from a combat vessel, or even for the use of other systems less sensitive to the speed of the missiles: jamming, decoy or directed energy weapons. In this context, it also seems possible to disrupt the very complex and inseparable chain of engagement or “kill chain” of these weapons: aircraft, drones or satellites necessary to provide the position and identification of the targeted vessel. But in order to be able to react against these weapons, appropriate means of detection are necessary: radars with a sufficient refresh rate to follow the maneuvering of the missiles, collaborative watch pooling the sensors arrayed around a battle force, UHF radar for very long-distance warning and satellite alerts. Finally, the short reaction time required for the destruction of hypersonic missiles requires high-performance decision-making aids to avoid untimely interception attempts which would lead to saturating the defense systems and quickly emptying the ammunition magazines.
Beyond the media hype that surrounds them, conventional hypersonic missiles are not yet the “infallible weapon” or “game-changer” that would make all their slower competitors obsolete. This is particularly the case when it comes to attacking moving platforms like naval ships, where the targeting chain is all the more complex as it is established at a great distance. These new missiles are both slower and more easily detectable than ICBMs for hitting fixed targets at very long distances. Their ability to hit targets in motion has yet to be proven. China seems well aware of those limitation : despite American investments in hypersonics, including anti-ship missiles, the Chinese PLAN (People’s Liberation Army Navy), continues to prioritize its ability to deploy a carrier battle group capable of conducting power projection operations. A new type of aircraft carrier is currently brought into active service every 7 years by Beijing.
Nevertheless, developments in hypersonic technology show that in high-end combat, subsonic offensive solutions, even when made very stealthy, are today overtaken by technologies based on very high speed and high maneuverability. Like the transition to supersonic in its time, hypersonics must be the subject of studies and development to understand the pros and cons of these weapons. It is a question of analyzing both the offensive realities and their exploitable flaws. We must measure the consequences of opening this Pandora’s box of proliferation which has hitherto been kept tightly closed by international strategic arms treaties. In particular, attacking moving targets with hypersonic missiles remains a challenge, leaving the Navy with room to maneuver (literally and figurately) against them. Indeed, in order to respond to such lightning strikes by fast-moving weapons, warships have an unrivaled advantage: on a single mobile platform, they combine the most effective air defense system, constituting detection, evaluation, decision-making capabilities and anti-missile systems, at the same time presenting to the enemy the most effective IADS and the most complex targeting problem that exists today.
 A French equivalent of the US Navy CEC is being developed with already a first capability with the cooperative naval surveillance tested during NATO “Formidable Shield” 21 live-fire Integrated Air and Missile Defense (IAMD) exercise
 In May 2021, the British press mentioned suspicions of spying on Graphene studies at the university of Manchester by Chinese students. Graphene is a material well adapted to build thermal shields.
 On 19th November 2021, the MDA announced the selection of Lockheed Martin, Northrop Grumman and Raytheon missile defense to produce the GPI system.
 SM-6 Block-IB should be equipped with a 21’’ rocket propeller able to enhance the range of the missile and reach hypersonic speed
About the authors
Captain Jerome Henry is the former officer in charge of future offensive capabilities at the French Navy HQ including hypersonic missiles. He is a graduate from the French Naval academy and from the British Advanced Command and Staff Course. He has a master’s degree of engineering sciences from the Naval Academy. In 2016, he graduated from the King’s College London with a Master of Arts in Defense Studies. He has been serving in the Navy for 23 years on several surface ships including 5 years onboard the aircraft carrier Charles de Gaulle. CPT Henry is currently the XO aboard Air Defense FREMM Frigate Lorraine.
Rear Admiral Emmanuel Slaars is a former commanding officer of Air Defense Destroyer Chevalier Paul, notably in charge of the protection of CVN Charles de Gaulle during all her operational deployment from 2014 to 2016. As such, he has been Air Defense Commander for two carrier strike group (USS Harry S. Truman and FS Charles de Gaulle) while they were engaged in dual carrier operations in the North Arabian Gulf. He olds a master’s degree of engineering science from the Ecole Nationale Supérieure d’Arts & Métiers and is a graduate from both French Ecole de Guerre and Collège des Hautes Etudes Militaires (CHEM). He is a naval officer for 29 years and has served 18 years at sea aboard destroyers, SSN and as head of Charles de Gaulle CSG’s staff. RADM Slaars is currently French Joint Force Commander in Indian Ocean (ALINDIEN).