Nearly six decades after the Outer Space Treaty banned military activities in space, its norms appear to be losing their power.
In May, U.S. officials from the Defense and State Departments disclosed the possibility of Russia deploying a nuclear-detonation device into space, and that a suspected testbed satellite had already been in orbit for two years.
China, meanwhile, has embarked on a campaign to expand its strategic nuclear forces beyond the numbers required for “minimum deterrence” and develop new delivery platforms, including a fractional orbital bombardment system.
Chinese and Russian interest in space nukes derives from their expressed anxiety over the U.S. strategy of deploying large and widely dispersed satellite constellations, such as the Space Development Agency’s “Proliferated Warfighter Space Architecture,” as well as commercial networks such as SpaceX’s Starlink communications satellites. SDA Director Derek Tournear has described his agency’s “proliferation” as a game-changing strategy of resilience, using numbers and architecture to keep U.S. space networks working despite single-point attacks via kinetic, directed-energy, or electromagnetic means. However, this has threatened the sense of “space deterrence” gained by China and Russia through their own investments in anti-satellite weapons. Using nuclear effects to hold entire orbital regimes at risk offers an alternative way to counter such proliferated constellations.
Yet not all nuclear detonations in space are equal. Understanding the different Russian and Chinese concepts for nuclear ASAT weapons, so far as they are understood in the public realm, will be crucial to any multilateral efforts to secure the space domain.
Russia aims high…
In early May, Assistant Secretary of State Mallory Stewart said Russia had not yet deployed an operational nuclear device in space, and, even if they had, it would not directly threaten human life. She did disclose, however, that Russia had launched a test satellite. “Russia has publicly claimed that their satellite is for scientific purposes,” Stewart said. “However, the orbit is in a region not used by any other spacecraft—that in itself was somewhat unusual – and the orbit is a region of higher radiation than normal lower-Earth orbits.”
Amateur observers quickly identified the satellite as Cosmos-2553 and its unusual orbit to be 2,000 km up, at the upper edge of low-Earth orbit, or LEO. Ostensibly carrying a synthetic aperture radar payload, Cosmos-2553 may have secondary payloads or otherwise be used to help understand the radiation and electromagnetic environment relevant to a nuclear ASAT program.
In Congressional testimony, then-Assistant Defense Secretary John Plumb revealed a rationale for why that might be important.
“Some [satellites] would be caught in an immediate [nuclear] blast, which they would not be able to survive the flux of that. And then others could be damaged over time…if [the] Van Allen belts are pumped,” Plumb told lawmakers.
Plumb was referring to the Van Allen radiation belts that surround Earth. Cosmos-2553 orbits within the inner Van Allen belt—much higher, incidentally, than the infamous 1962 Starfish Prime nuclear detonation by the United States that damaged or disabled one-third of the satellites in orbit at the time. U.S. analysts appear to believe that the Russian nuclear ASAT intent is to rapidly “pump” the inner Van Allen radiation belt and transform areas of low-Earth orbit and some higher altitudes into high-exposure zones.
Most satellites in LEO are designed to operate in a relatively benign radiation environment, given the natural protection of Earth’s magnetic field. Satellites in higher orbits are generally built to withstand higher radiation exposure, so they would be less susceptible than their more numerous compatriots closer to Earth. A nuclear blast 2,000 km up would likely not cause much immediate damage, but repeated passes through artificially augmented radiation belts could quickly degrade satellite electronics. Sun-synchronous satellites and any others with inclinations taking them through energized field lines would be the first to fail.
This effect would also linger. Plumb indicated that the effects of a Russian attack might last a year. High-energy particles released by Starfish Prime stayed in orbit for at least five.
…while China goes low
Beijing appears to have different ideas about nuclear detonation in space.
China’s leading military technologists and strategic thinkers have identified space as the linchpin for U.S. military operations, with a remarkably close reading of U.S. military concepts and verbiage.
For example, Wu Mingxi, chief scientist at one of China’s largest military conglomerates and author of an influential book on the future of warfare, writes, “In space-based information network construction and space-based information applications, the United States is the leader.…Through the practice of war, they have accelerated space-based information applications and increased the pace of progress…greatly decreasing the time of their ‘Observe, Orient, Decide, Attack’ (OODA) loop.”
Col. John Boyd defined the final segment of his OODA loop as “act,” but here Wu rendered it as “攻击” or “attack.” The central thesis of Wu’s vision is not to overmatch the United States in a correlation-of-forces contest, but to change the terms of conflict by unleashing a networked system-of-systems powered by AI to react exponentially faster than an opponent.
Using nuclear detonation to strike a critical blow to U.S. space assets would severely hamper the operational tempo of U.S. forces, despite the SDA’s proliferated networks.
A review of literature of PRC papers on nuclear detonation in space has shown a steady progression from relatively crude simulations of burst-shell dynamics to fine-tuning the parameters of a detonation to achieve different shapes and effects. Advancements in AI and supercomputing also allow research and planning that was not possible back in the Cold War. China has the capacity to model these nuclear detonations precisely without the need for real-world testing, which is prohibited by international treaties.
In contrast to the apparent Russian model of pumping the Van Allen belts from above, PRC research has focused on using atmospheric effects from below LEO, generating ionizing radiation and high-energy particles closer to Earth. Such effects could be more finely modulated with yields as low as one kiloton.
One potential delivery means might be the FOBS-Hypersonic Glide Vehicle hybrid platform that China demonstrated in 2021. It could carry a warhead to any point around the Earth, but in a different path than traditional ballistic missile delivery, making it less likely to be perceived as a strategic nuclear attack.
A detonation from below LEO would produce immediate radiation effects on any satellites within line-of-sight. A localized augmented artificial radiation belt and a plume of radioactive debris might persist for weeks or longer.
Such a weapon would still be indiscriminate and affect any satellite passing through the region. Closer to Earth, such a device would also generate an electromagnetic pulse propagating downward through the atmosphere to affect any unshielded terrestrial electronics, particularly long-distance wires such as power lines or telecom cables. Still, a single shot would be less global in scale and shorter in duration than the above apparent Russian nuclear ASAT.
Intentions matter
How likely are China and Russia to implement such an extreme and treaty-breaking plan for weaponizing space?
After China’s 20th Party Congress in 2022, party leaders directed its military to “construct a strong strategic deterrence force structure,” and face down the “myriad cross-domain challenges of a networked space force.” To create this new deterrence force structure, the People’s Liberation Army was directed to go beyond traditional thinking and use both nuclear and conventional forces in new ways.
In Russia, Vladimir Putin revealed novel nuclear doomsday devices in 2018 and has since repeatedly rattled his nuclear sabers during his invasion of Ukraine. Prominent Russia analyst Masha Gessen concluded that Putin is determined to foist new nuclear doctrine on the world.
One aspect that is still unclear about either mode of nuclear ASAT is whether the warhead would be a thermonuclear or fission bomb. Fusion detonations are more efficient at producing prompt radiation effects, while a fission bomb might be more effective at contaminating the space environment with persistent radioactive flux. After Starfish Prime detonated a thermonuclear warhead 400 km up, Apollo program engineers were particularly concerned about an explosion doped with uranium-238, which would generate a higher concentration of beta particles and other fission debris, pumping the Van Allen radiation belts “a hundredfold.” A specially designed warhead could optimize the destructive advantages of both.
In April 2024, the international community called upon Russia and China to recommit to their obligations as signatories to the Outer Space Treaty and its prohibition against deploying nuclear weapons in space. Tellingly, Russia vetoed the UN Security Council resolution and China abstained. For the sake of the global commons, the urgency to forestall and reverse the weaponization of space has rarely been higher.
David D. Chen is a Senior Analyst for BluePath Labs. He focuses on aerospace, cyber, and cross-domain emerging technologies and China’s military modernization.
P.W. Singer is Strategist at New America and the author of multiple books on technology and security, including Wired for War, Ghost Fleet, Burn-In, and LikeWar: The Weaponization of Social Media.
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