On October 21, during a debriefing with Vladimir Putin and Valery Gerasimov, Chief of the General Staff of the Russian Armed Forces, the first operational test of the 9M730 Burevestnik (“Procellaria”), a nuclear-powered cruise missile codenamed SSC-X-9 Skyfall by NATO. The Russian president described the new weapon as “very promising” and “a unique product that no other country has.” . All Western media outlets were quick to give grandiose definitions of the Burevestnik: “new nuclear challenge,” “invincible weapon,” but also “propaganda weapon.” What does this new missile really represent?
The Burevestnik and the Russian Federation’s new “strategic superweapons”
Over the past two years, the Russian Federation has unveiled three new strategic weapons, one of which is already in operational use in the field, the Oreshnik (“Hazel Tree”). The other two, on the other hand, are true doomsday devices, as they can only or mainly be used for strategic nuclear attacks: the nuclear-powered Burevestnik missile and the Poseidon underwater drone torpedo, which is also powered by an atomic engine.
The Burevestnik represents a sort of “holy grail” of aerospace propulsion and is an old acquaintance for those who follow Russian military affairs, having been announced several years ago. The project was previewed on March 1, 2018, in the Russian president’s annual address to parliament as one of six new strategic superweapons, супероружие. In addition to the Burevestnik, the 3M22 Zircon, a ship-launched hypersonic cruise missile, the Kh-47M2 Kinzhal, a hypersonic aeroballistic missile, the Avangard hypersonic reentry vehicle, the RS-28 Sarmat intercontinental ballistic missile, and the Poseidon underwater drone torpedo.
The Poseidon and the Burevestnik represent a kind of unique weapon in nuclear deterrence. The former is a kind of nuclear-powered torpedo drone capable of depths of around 1,000 meters (in comparison, the depths reachable by Russian and American SSNs currently in service rarely exceed 600 meters) and equipped with a thermonuclear warhead that can reach 2 megatons. A deterrent to complement the classic fleet of ballistic missile submarines, even more difficult to detect, but with less flexibility of use as the warhead would be a sort of underwater nuclear mine, intended to trigger a sort of tsunami, more or less radioactive, against enemy coastal targets. The weapon could also be used against military targets, such as aircraft carrier task forces, which could be annihilated with a single strike. It goes without saying that the use of such a powerful atomic weapon would represent either an escalation towards total exchange or its direct realization.
The Burevestnik, on the other hand, would be the aeronautical equivalent of the Poseidon: a cruise missile with nuclear weapons and atomic propulsion, which would potentially guarantee a virtually unlimited waiting circuit. This philosophy is not dissimilar to that of loitering munitions applied to nuclear weapons, or even the ad infinitum version of strategic bombers in permanent flight during the Cold War.
The ancestors of the Burevestnik: SLAM and Project Pluto
For analysts, the announcement of the Burevestnik remained in a sort of engineering limbo. Feasible from a technical point of view but impractical from an operational doctrine point of view. These were the conclusions reached by the United States, which had designed a similar weapon in the late 1950s, stopping at ground testing of two nuclear-powered ramjet prototypes between 1961 and 1964.
The Burevestnik and its American ancestor, the SLAM (Supersonic Low Altitude Missile), are unique weapons of their kind: they involve the application of atomic propulsion to cruise missiles, i.e., flying bombs capable of being piloted over enemy territory by a more or less automatic system.
Project Pluto for the development of SLAM was assigned on January 1, 1957, to the Lawrence Radiation Laboratory in Berkeley, California, by the US Air Force and the AEC, Atomic Energy Commission. The request was to develop a nuclear-powered missile to give the weapon virtually unlimited range. At that time, the US arsenal still lacked intercontinental ballistic missiles, and the only carriers for strategic atomic weapons were bombers such as the B-52, which had just entered service. ICBMs were still in development: the first US intercontinental missile, the Atlas, would fly for the first time on December 17, 1957, and there were still doubts about its operational capabilities with regard to launch. ICBMs also required an equipped launch site, preferably an armored silo, and at the time they were all liquid-fueled: a propellant that required long and even dangerous loading and—in case of launch postponement—unloading operations. The missile’s tanks could not remain full for too long, which slowed down the weapon’s deployment.
In comparison with the USSR, the United States was sweating bullets: even though the American nuclear arsenal was still ten times larger than the Soviet one, Moscow had apparently solved the technical problem of delivering bombs to the enemy: its R-7 Semyorka (SS-6 Sapwood in NATO code), the missile with which they had put Sputnik into orbit, was capable of carrying a nuclear warhead directly over US territory and could not be intercepted, unlike B-52 bombers or cruise missiles such as the Matador (which in any case had a range of only a thousand kilometers).
So US missile science was floundering. And in the Cold War mentality, where it was essential to annihilate the enemy with the first strike, the ICBM still seemed too clumsy and slow a weapon. At the Strategic Air Command, someone thought they could get around the problem: launch the missile and then keep it ‘parked’ in a waiting circuit.
To ensure unlimited range, a ramjet would be used, in which, instead of igniting the air with fuel to cause it to expand and provide thrust, as in common jet engines, the necessary thermal expansion of the air would be achieved by superheating it as it passed through an atomic pile.
The use of nuclear energy as a propulsion system was (and is) not the only technical obstacle for this type of aircraft: there is also the problem of managing high operating speeds.
A ramjet can only operate at speeds above Mach 1.5/2. Vehicles that use it must be accelerated with ordinary propulsion systems (turbojets or rockets) until the speed necessary for the air to flow into the ramjet at the appropriate pressure is reached. The SLAM was also designed to take off and accelerate with auxiliary rockets until the ramjet’s ignition speed was exceeded. At that point, the nuclear stack would receive compressed air from the inlet cone and superheat it, causing it to flow out of the outlet nozzle with sufficient thrust to further accelerate the missile. According to estimates, this first atomic ramjet could have propelled the missile to Mach 3 (3,000 km/h) with a range of 180,000 km: in just over two days, it could have circled the equator more than four times!
The SLAM, with a length of between 20 and 30 meters, would have been more like a large arrow-shaped fighter-bomber than a missile. The extremely high speeds predicted in theory presented the weapon with problems in terms of the materials to be used as well as its maneuverability.
Materials technology is therefore the main obstacle to these weapons. Specific materials are needed for the airframe, which is subject to extreme mechanical and thermal stresses, as well as specific materials for the parts in contact with the nuclear reactor, not only because of the operating temperature, but also because of the continuous bombardment of neutron radiation (“neutron poisoning”), which causes the more or less rapid degradation of the materials it affects (corrosion, helium bubbles, fragility, triggering of secondary radioactivity, etc.). Similarly, all electronic equipment must be radiation-proof.
If the SLAM had entered service, it would have been equipped with multiple free-fall warheads that it would have left along its path, and the attack would have taken place at low altitude, up to 150 meters above the ground. Beyond the nuclear warheads it would have scattered, the missile itself represented an apocalyptic weapon due to the characteristics of its low-altitude flight: traveling at three times the speed of sound, 200-300 meters above the ground, it would have emitted a supersonic wave capable of damaging people and property along its path. In addition, the jet exiting the nozzles, heated to over 1,300°, would also have been highly radioactive.
However, these considerations did not prevent the development of the vehicle from proceeding. A special site was built in a desert location in Nevada, called Jackass Flats, to test the engines. Unlike other experimental reactors of the time for propelling manned aircraft, the SLAM reactor was in fact an ‘air-cooled’ reactor with minimal shielding, as no human personnel were expected to be on board.
A highly automated test site was therefore built, which also had to simulate the entry of high-speed air into the engine through a complex compressed air pumping system. The first engine, designated Tory IIA, was fired up for the first time on May 14, 1961, and only for a few seconds at full power. It worked. The next development, designated Tory IIC and intended to equip the first prototype, was tested three years later, in May 1964, and underwent several tests, even for complicated periods.
But in the meantime, ICBM technology was advancing more rapidly, and project managers had begun to consider it risky to test such a weapon even in the middle of the Pacific Ocean. After all, the controversy surrounding the accident following the Castle Bravo test on March 1, 1954, was still raw, with hundreds of Marshall Islanders and Japanese fishermen passing through contaminated by the radioactive fallout from the first US H-bomb. So on July 1, 1964, the project was canceled.
However, the millions of dollars spent had led to the development of new ceramic materials capable of withstanding high temperatures, new reactor technologies, and unexpected advances in medicine. Project director Ted Merkle, who had renamed the weapon “the flying crowbar” because the system was supposed to be highly reliable, died of liver cancer in 1966. Merkle had, however, had time to use the laboratory’s computers to develop one of the first CAT systems.
Historical aside: nuclear turbojets
Nuclear ramjets such as the Tory II were not the only form of nuclear propulsion in aviation in the 1950s and 1960s. In 1955, the HTRE (Heat Transfer Reactor Experiment) adventure began, a nuclear reactor that was supposed to power General Electric’s modified J53 turbojets.
The principle was similar to that of the nuclear ramjet: the combustion chamber where the compressed fuel in the first stage was ignited was replaced by heat exchange with the reactor. Unlike the nuclear ramjet, the atomic turbojet could run on normal aviation fuel for ignition.
The first prototype, the HTRE-1, was ignited in January 1956 to test whether the concept of the “atomic turbojet” could work. Thrust and shielding proved insufficient, but the concept worked. To reduce weight and improve shielding and performance, the HTRE-1 was modified into the HTRE-2, and then the HTRE-3 was developed, which used two turbojets. With the HTRE-3, a prototype capable of providing the necessary thrust was achieved in March 1958, but the production of a flying prototype was still a long way off.
The atomic turbojet was defined as “direct cycle” because, as with the SLAM missile’s ramjet, the air passed directly through the reactor.
Pratt & Whitney was working on a more complex, indirect design in which the air in the turbojet was heated by a liquid sodium heat exchanger that also cooled the reactor. Although the advantages in terms of radiation containment were greater, allowing for weight savings on shielding, the system proved too complex and never reached the prototype stage.
While the engines were being tested on the ground, a specially modified Convair B-36 Peacemaker (the giant transcontinental bomber that was the backbone of the Strategic Air Command until the advent of the B-52) was fitted with a 1-megawatt liquid sodium reactor, designated the Aircraft Shield Test Reactor. The reactor was not intended for propulsion, but was installed solely to test the effects of radiation in flight. The reactor, mounted in the rear of the fuselage, was separated from the crew compartment by a 4-ton lead disc, almost 10 cm thick. The crew compartment itself consisted of an 11-ton tank made of lead, steel, and rubber. Additional protection was provided by water tanks. The windshield was made of leaded glass panels several centimeters thick.
A total of 47 flights were made, lasting 215 hours, during which the reactor was only turned on for 89 hours. The inseparable companion of the aircraft, designated NB-36H, was a Boeing C-97 Stratofreighter, carrying a platoon of Marine paratroopers, who would have had the thankless task of ‘securing’ the area around the NB-36H in the event of accidents or emergency landings. It seems that they were nicknamed the ‘glow-in-the-dark platoon’: the phosphorescent patrol.
However, progress on the atomic aircraft program was extremely slow, and President Eisenhower eventually cut off funding after a billion dollars had been spent, and in March 1961, the program was shut down.
The Soviets had also been studying a nuclear reactor for aircraft propulsion during those same years. A nuclear reactor was installed on a Tupolev Tu-95 designated Tu-95LAL, which made about forty test flights. Meanwhile, on the ground, engineers were evaluating which type of engine was most suitable for nuclear propulsion: turbojet, ramjet, and even turboprop, but they did not produce working engine prototypes like the Americans did.
Nuclear thermal rockets and satellites powered by atomic reactors
For the sake of completeness, it is worth mentioning that the last type of nuclear propulsion studied by the Americans and Soviets, which reached the prototype stage, was for extra-atmospheric rockets intended for space exploration: hydrogen is ‘heated’ by the reactor and then expelled from the nozzle, generating thrust. Both the Soviets, with the RD-0410, and the United States, with the NERVA project, built prototypes but did not reach operational use.
In this case, since a propellant, hydrogen, is involved, it is clearly not a system with unlimited autonomy, unlike ramjets, which draw propellant from the atmosphere and simply superheat it with their nuclear reactor: theoretically, as long as the reactor has fissile material, the missile can remain in flight.
A review of the projects of the 1950s and 1960s allows for one last mention for those who see a nuclear reactor as something complex and delicate that can at best be put on a ship. In reality, both sides of the Iron Curtain experimented with satellites powered by “nuclear batteries.” The technical definition would be radioisotope thermoelectric generators, based on small reactors such as the US SNAPs or the Soviet Topaz. In particular, the latest evolution of the Soviet liquid metal Topaz aroused the interest of the United States in the early 1990s, which acquired six for ground testing. Although the concept of a “space atomic battery” is different from that of a “nuclear ramjet,” the mention of the Topaz II is not so out of place: during a speech by Putin on a visit to the military hospital in Mandryka, the Russian space program was brought up, stating that Burevestnik technology will be used for the Russian lunar program (!) and that Burevestnik‘s electronic radiation protection systems are already in use in the space program.
Why resurrect a weapon system that was abandoned sixty years ago?
Nothing is known about the Burevestnik’s propulsion system. The weapon’s philosophy and Russian-Soviet experience with ramjets would suggest a nuclear ramjet like that of the US SLAM. This is despite the fact that the data from the first test, 14,000 km in 15 hours, shows a subsonic weapon, and therefore a speed profile that is not optimal for a ramjet (but subsonic ramjets also exist: in 1939, the Soviets enjoyed installing ramjets on Polikarpov biplanes). The subsonic speed has led some to speculate about a subsonic nuclear turbojet, which is less likely but still possible.
Nuclear propulsion in aviation is therefore nothing new. The main limitation that has (fortunately) prevented its use so far was not so much the lack of adequate shielding, but rather the fact that it offered no advantages compared to its extremely high costs and operating risks.
Yet in the early 2000s, Russia deemed it appropriate to resurrect a Cold War ghost that had not yet seen ICBMs deployed. The theoretical advantage of a weapon such as SLAM, adapted to current technologies, is that it combines the advantages of a cruise missile with a low-altitude mission profile (such as today’s SCALP/Storm Shadow) with a virtually unlimited range that would allow an attack trajectory that passes where the enemy is least defended.
For example, if a possible exchange of Cold War ICBMs naturally involved an Arctic route scenario, a Burevestnik could approach by circling around the Antarctic, perhaps climbing the mountain ranges of South America up to the Rocky Mountains. Furthermore, given its autonomy, it could simply be “parked” in a holding pattern, like an airplane waiting its turn at a crowded airport. For optimists, however, the longer a weapon of this kind remains in flight, the easier it will be to intercept and shoot down, which would make it much less effective than many weapons already in arsenals.
The real unknown factor of a weapon such as the Burevestnik remains its heat signature, which is certainly greater than that of a conventional cruise missile. And the possible radioactive trail, if the propulsion were similar in terms of materials and heat exchange to that tested for the SLAM sixty years ago.
Objectively, if it were a subsonic missile, the advantage of being able to remain in flight would not be a particularly decisive factor. If the Burevestnik were supersonic or hypersonic, on the other hand, it could offer some objective strategic advantages by greatly reducing its chances of interception.
The 2018 accident
The fact is that the Russians have decided to get serious. In August 2018, an explosion occurred on an offshore platform in the Nënoksa naval range, northwest of Arkhangelsk, killing seven people and injuring six others. Five victims were thrown into the sea, and two others are believed to have died from the effects of radiation. At the time, radioactivity levels were found to be 16 times higher than normal.
In November, the victims’ families received posthumous honors directly from Putin himself, who took advantage of the occasion for a cryptic propaganda operation, stating that they were working on an “unparalleled weapon”: “We are talking about the most advanced and unparalleled ideas and technical solutions in the field of weapons design to ensure Russia’s sovereignty and security in the coming decades.”
The assumption is that he was talking about the Burevestnik, even though Rosatom’s statement on the increase in radiation spoke rather generically of an ‘isotope power source for a liquid-fuel rocket engine’, which would rule out the ramjet. It is possible that the 2019 accident was related to the recovery of an early prototype of the Burevestnik tested in 2017, which ended up in the sea after just 35 km.
Not just propaganda: The War Zone recalls that these areas have seen the Boeing WC-135 Constant Phoenix, aircraft equipped to detect radiation in the air, fly over them on more than one occasion. The last time was at the end of August in the Baltic Sea off the coast of Estonia. For the moment, however, Norway has not detected any changes in radioactivity, unlike in 2018.
Perhaps the winds have not yet carried the effects of radiation from the missile, which was plausibly tested at the Pankovo test site, in the Novaya Zemlya archipelago, more than a thousand kilometers northeast of Nyonoksa, the site of the 2018 accident. Or perhaps the Russians have indeed developed a low-radioactivity nuclear aircraft engine. Or more simply, the Burevestnik is just a bluff born of Putin’s propaganda.
L‘Oreshnik and the question of materials
Of course, there remains the real possibility that the Russians have succeeded in building an indirect-cycle nuclear ramjet (or turbojet), in which heat exchange with the reactor takes place via a liquid metal cooling circuit. This would allow for lower radiation dispersion. This is something the United States failed to achieve in the 1960s for its SLAM. In a sense, the issue concerns materials more than nuclear engineering.
The problem of materials is in fact directly linked to the construction of miniaturized nuclear reactors with indirect cooling and shielding systems for the vehicle’s avionics, as well as the problem of fuselages.
And the reflection on materials should be related to some hypotheses about the ‘inert’ MIRV warhead of the Oreshnik missile launched against the Pivdenmash aerospace factory in Dnipro on November 21, 2024.
Without bothering Putin and his sensationalist statements about weapon systems based on ‘new physical principles’, the unknown nature of the Oreshnik’s inert warhead deserves further consideration, especially in light of the feasibility of the Burevestnik.
According to reconstructions, the Oreshnik used in Ukraine would have dropped six MIRV warheads on the target, all inert. However, at the re-entry speed of this weapon (estimated at 3.4 kilometers per second), each kilogram of inert warhead weight is capable of producing an impact energy equivalent to at least 1.5 kg of TNT.
Meanwhile, we do not know at this time whether the inert warheads were actual kinetic weapons (i.e., designed to maximize impact) or simply “test ballast.” Regarding the attack, it is certain that the holes in the factory roof were, all things considered, “minimal.” Pure evidence indicates that there were fires in the factory for at least three hours. Were these fires caused by the material found in abundance in a factory that produces aerospace material? Or were they triggered by the high kinetic energy of the projectiles, which ionize the air due to friction and therefore reach the target with an aura of incandescent plasma, as evidenced by footage of the attack? And how much of the Oreshnik’s kinetic projectile would have been consumed by friction in the atmosphere and how much of the projectile would have impacted the target? There is no way of knowing.
However, orbital kinetic weapons would be nothing new in the West. First theorized by scientist and science fiction writer Jerry Pournelle in the 1950s, under the name Project Thor (or ‘God’s rods’), they envisaged a satellite armed with six-meter-long tungsten ‘rods’ with a diameter of 30 cm, weighing about 8.2 tons, which would plunge to the ground at hypersonic speed, generating an impact force equivalent to 15 tons of explosives. The project was reevaluated in the early 2000s by the US Air Force with the Hypervelocity Rod Bundles, also dropped from armed satellites. It should be noted that treaties on the military use of space do not explicitly prohibit kinetic energy weapons such as “God’s rods,” because the Outer Space Treaty (1967) prohibits the placement of weapons of mass destruction in orbit but not kinetic weapons.
If the dummy warheads of the Oreshnik were kinetic weapons in all respects, as it seems, the Russians would have succeeded in carrying out a kinetic bombardment without the need for armed satellites, which, although not directly prohibited by the 1967 Treaty, would still be contrary to its spirit.
The unknown factor remains the materials used for the kinetic projectiles. This unknown factor goes hand in hand with the functioning of the Burevestnik. If we take the Russian statements at face value, then they would have made progress in the field of materials, and the madness of a nuclear ramjet would not be so crazy after all.
Conclusions
Russia’s new strategic triad puts the country’s competitors, essentially the EU and the US, in a stalemate.
Strategic nuclear weapons are intended to intimidate potential adversaries, inhibiting their willingness to seek a first strike in order to win a nuclear war with the first blow. In the logic of MAD (Mutual Assured Destruction), no matter how heavy the first surprise strike may be (assuming that this can be achieved), the enemy will always have such devastating retaliatory potential that the term ‘victory’ becomes completely meaningless.
Weapons such as the Poseidon are designed precisely for this purpose: conceived to be concealed in the depths of the ocean without being intercepted, they could inflict unimaginable damage on the countries of the Rimland (the “maritime belt,” which in classical geopolitics corresponds to the Anglosphere plus Europe and Japan): more than a third of the population of NATO countries lives in coastal urban agglomerations, which would be the prime target for retaliation with Poseidon missiles armed with thermonuclear warheads.
The Burevestnik, on the other hand, appears more like a display of technological superiority than a real weapon of decisive power. Even if it were indeed hypersonic, a circling missile would still be easier prey for missile defenses, especially when compared to maneuverable hypersonic nuclear warheads (MARVs) or hypersonic aircraft such as the Avangard installed on intercontinental ballistic missiles. Once again, therefore, ballistic missiles prove to be superior to cruise missiles, especially now that the Russians are deploying mainly solid-fuel weapons, which can be launched very quickly, and have developed liquid-fuel missiles that can be rapidly deployed: it takes about one minute to get an RS-28 Sarmat (NATO code: Satan 2) ready for launch. At present, the Russians have about 200 RS-24 Jars (NATO code: Sickle C) units, with sufficient range to strike the entire NATO bloc, equipped with multiple independent warheads and solid propellant, capable of being launched even from rotated platforms. Starting next year, the Sarmat will also begin to be deployed.
More decisive in redrawing the strategic balance, however, appears to be the Oreshnik, which could be used as a weapon for ‘surgical’ strikes in a possible escalation with NATO powers without having to resort to nuclear weapons. The almost total invulnerability to interception of its hypersonic kinetic warheads makes this weapon ideal for ‘telephone’ attacks, which yield high political, propaganda, and tactical dividends without incurring accusations of ‘indiscriminate’ or ‘terrorist’ attacks that could follow the use of even very low-yield nuclear weapons.
In any case, counterintuitively to what most of the public believes, strategic offensive weapons represent an improvement in stability and a reduction in the risks of nuclear conflict. With all due respect to the iconic ‘Doomsday Clock’ of the Bulletin of the Atomic Scientists, the emergence of new and increasingly deadly offensive weapons has the effect of discouraging a possible enemy attack but does not encourage one’s own commanders to take the initiative, since there is no wunderwaffe capable of ensuring a first strike so deadly and definitive as to prevent the inevitable enemy retaliation. Even if Russia decided—in a moment of total and completely unthinkable madness—to attack NATO with all this array of weapons, nothing would save it from a counterattack more than sufficient to annihilate over 60% of its population and industrial-military capacity. The same applies if the roles were reversed, even if the US were to deploy all its superiority in terms of ‘stealth’ bombers and ballistic missile submarines.
This means that the only real risk of nuclear war lies with political classes that do not have a clear understanding of the overall picture, namely that there is no possibility, no ‘good cause’ or no ‘game changer’ capable of transforming a direct confrontation between NATO and Russia into anything other than mutual, total suicide.
[Photo: By Mil.ru, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=172703679]
