Russia is developing a nuclear-weapons-based anti-satellite (ASAT) capability, and the Western democracies must work together to prevent Moscow from deploying such a weapon. This will be an immediate and important challenge, testing the next US administration and its ability to work with allies to ensure stability and security in space.

Were a deployment of a nuclear ASAT to go ahead, Russia would deliberately violate the 1967 Outer Space Treaty, which is a key foundation of international space law. Militarily, a nuclear weapon in orbit would indiscriminately threaten a vast number of satellites and create an effective nuclear sword of Damocles threatening the national security of many states, especially given the growing dependency of Western democracies on the space domain for their national security and economic prosperity.

The news that Russia is developing a nuclear-weapons-based ASAT capability broke mid-February in a leak from the chairman of the US House Permanent Select Committee on Intelligence, Representative Mike Turner. The Biden administration eventually responded, noting that the nature of the weapon under development by Russia suggested that ‘it would be space based. And it would be a violation of the Outer Space Treaty to which more than 130 countries have signed up to, including Russia.’ That reinforces the perception that Russia is indeed developing a capability to place nuclear weapons in orbit around the Earth in direct violation of the treaty.

Article IV of the treaty states that ‘States Parties to the Treaty undertake not to place in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner.’

The 1967 Outer Space Treaty is considered the foundation of modern international space law. A deliberate Russian violation of Article IV would fatally undermine the entire treaty, reversing decades of progress towards avoiding an uncontrolled arms race in space.

Russia subsequently vetoed (and China abstained on) a US- and Japanese-sponsored UN Security Council resolution, tabled on 24 April 2024, calling on all states to reaffirm their support for the Outer Space Treaty. A second resolution, sponsored by Russia and China and tabled in May 2024, called for a ban on the placement of any weapons in space, but that was vetoed by the US, France and Britain; the US noted that Moscow had recently deployed an ASAT on 16 May into an orbit to threaten a US satellite, thus suggesting that the Russian- and Chinese-sponsored resolution was designed to preserve their military advantage.

Furthermore, the lack of clear information on the Russian nuclear ASAT capability released by the Biden administration so far has to a certain extent created confusion within the space policy community. For example, there has been discussion of another satellite, which was launched in February 2022. Known as COSMOS 2553, the satellite was deployed into a high part of the low-earth orbit (LEO) band, at an altitude of 2100km. This is in a region, noted US Assistant Secretary of State for Arms Control, Deterrence and Stability Mallory Stewart, ‘not used by any other spacecraft … and the orbit is in a region of higher radiation than normal lower Earth orbits, but not high enough of a radiation environment to allow accelerated testing of electronics as Russia has described the purpose to be.’ Yet researcher Pavel Podvig argues that this satellite is in fact entirely separate from the nuclear-ASAT program, even though earlier media misreporting suggested it was linked to it. It is, in fact, a Neitron radar reconnaissance satellite.

The use of a nuclear-weapons-based ASAT capability would generate an electromagnetic pulse. That would indiscriminately threaten any satellites within visual range of detonation. The military effects of high-altitude nuclear detonations are clear in terms of threatening substantial numbers of satellites, as well as crewed space stations such as the International Space Station and even China’s Tiangong space station. The risk from large-scale damage across hundreds or even thousands of satellites would be the long-term denial of access to space for decades or longer.

There’s a longer term challenge if Russia violates Article IV of the Outer Space Treaty. The article also states that ‘the Moon and other celestial bodies shall be used by all States Parties to the Treaty exclusively for peaceful purposes. The establishment of military bases, installations and fortifications, the testing of any type of weapons and the conduct of military manouvres shall be forbidden.’ So, a Russian deployment of a nuclear ASAT capability that invalidated Article IV, and, with it, the Outer Space Treaty as a whole, would in effect kick open the door to the militarisation of the Moon.

With China, as well as Russia, determined to establish a permanent presence on the lunar surface in the 2030s, the removal of Article IV of the 1967 Outer Space Treaty would free up those states to establish a military presence on the lunar surface to claim ownership of resource-rich areas. This is particularly worrying for the longer term sustainable and responsible use of space, particularly against the context of likely intensifying astro-strategic competition over presence and access to space-based resources between states and non-state commercial actors in coming decades. More broadly, the collapse of the treaty would dramatically weaken any potential basis of trust for establishing credible and effective norms of responsible behaviour in space. Although space is not yet a lawless wild-west domain, the removal of that vital foundation established by the treaty means that creating laws that can be enforced to prevent uncontrolled arms racing, or stop the use of force to grab territory and resources, becomes much more difficult in the future.

The Russian development of a nuclear ASAT capability is an immediate threat to Western security and a long-term challenge to established norms of responsible behaviour in space. The dilemma that faces Western democracies is how to prevent the deployment of such a capability, and, ideally, reverse its development. International legal and diplomatic pressure within the Security Council seems to be going nowhere, and imposing sanctions that will actually be enforced is also problematic if states such as China, Iran and North Korea—Russia’s partners in an axis of authoritarian powers—veto such efforts within the council or violate them at will. This dilemma highlights the challenge of international space law: the enforcement of existing legal agreements. Space law can’t be effective if it can’t be enforced.

The solution will require greater consideration of deterrence through denial and punishment—and greater emphasis on building space resilience if the first casualty of a Russian nuclear ASAT capability is the 1967 Outer Space Treaty. That will demand new and innovative thinking on space domain awareness and space control by the US and its allies. A continued drift forward through a strategy of hope that Russia will honour its obligations under space law even as the West is under direct threat from Moscow is a strategy for failure.