Russia’s Alleged Nuclear Anti-Satellite Weapon: International Law and Political Rhetoric
The development and testing of anti-satellite weapons (ASATs), as well as debates concerning the legal and policy implications of ASAT testing and use, have existed since soon after the dawn of the Space Age. The centrality of these issues has waxed and waned over time. However, recent years have seen renewed testing of destructive ASATs (such as missiles) that spawn orbital debris and of rendezvous and proximity operations by satellites that may actually be tests of on-orbit ASAT capabilities.
There is no treaty explicitly banning ASATs. However, in April 2022, U.S. Vice President Kamala Harris announced a unilateral moratorium on destructive ASAT testing by the United States and invited other States to join. As of October 2023, 37 States had made similar announcements and, with the support of 155 States, the UN General Assembly passed a resolution (A/RES/77/41) that backed a moratorium on testing direct ascent ASATs. Russia, China, and India, all of whom have tested ASAT technologies in recent years, did not support such a moratorium.
This recent activity has fomented a particular sense of redoubled activity and urgency. This post considers current debates over the use of ASATs in light of Russia’s alleged program to develop a nuclear weapon for deployment in Earth orbit as an ASAT. It will review allegations that Russia is developing such a weapon, briefly summarize international legal obligations related to ASATs and to weapons in space, consider recent UN Security Council (UNSC) debates, and contextualize the controversy in light of Russia’s and the United States’ likely strategic goals.
Russia’s Alleged Nuclear ASAT Program
In February 2024, Rep. Mike Turner, the Chairman of the U.S. House Permanent Select Committee on Intelligence, announced there was a “national security threat” concerning a “destabilizing foreign military capability.” National Security Council spokesperson John Kirby stated the capability was “related to an anti-satellite weapon that Russia is developing.” Further statements by U.S. government officials explained they had concluded the system was only in development and not yet deployed. Additionally, some experts believed that a non-nuclear satellite that had been launched and placed in a very high orbit in 2022 might be part of this development program.
Russia’s response to the United States’ claims shifted within a couple of days. Initially, Russia called it “malicious fabrication,” but later signaled its willingness to discuss the matter with the United States “if there are such initiatives from the American side.” Russia’s rhetoric focused on the maintenance of international law. President Putin stated, “Our position is clear and transparent: we have always been categorically against, and are now against, the placement of nuclear weapons in space. . . . On the contrary, we call for compliance with all agreements that exist in this area and proposed to strengthen this joint work many times over.”
The United States, Russia, China, and other countries have demonstrated or are developing capabilities that could be used for a variety of purposes, including surveilling, damaging, or destroying foreign satellites. In particular, Russia, China, the United States, and India have conducted tests of destructive ASATs. However, recent kinetic tests were for techniques that would only target one satellite at a time, such as using a missile launched by a plane or a projectile fired from another satellite. (These kinetic methods are in contrast with cyber operations, which can affect more than one satellite at a time.)
If such demonstrations of kinetic ASATs are meant to warn foreign adversaries, those warnings are less worrisome in an era when a few “big juicy targets” in space are being replaced by large networks of small, cheap, and replaceable satellites, sometimes called “megaconstellations” or “proliferated low-Earth orbit (LEO)” constellations (see also comments by Brian Weeden, formerly of the Secure World Foundation). While the 1991 Gulf War provided evidence of the effectiveness of U.S. precision munitions using the Global Positioning System (GPS), the importance of megaconstellations such as Starlink have become clear in the war in Ukraine. In 2023, General James H. Dickinson, then the head of the U.S. Space Command, remarked “[h]aving a megaconstellation, quite frankly, frustrates our adversaries . . . because you don’t know how many satellites it would take to have any kind of a degradation to that architecture, or which one if you had to pick one, you would have to, you know, have an effect against.” Facing a megaconstellation, an ASAT that targets one satellite at a time might be like using a flyswatter against a swarm.
However, a single nuclear weapon might be able to destroy hundreds or even thousands of satellites. As Sandra Erwin wrote in March 2024, “[s]ome analysts believe Russia may be contemplating the nuclear option in response to the growing prominence of SpaceX’s Starlink system, which has provided vital communications assistance to Ukrainian defense forces.” When the United States detonated a 1.4 megaton warhead in 1962 in the Starfish Prime test, at least six of the approximately twenty-four satellites then in orbit were damaged or destroyed. Whether a nuclear weapon detonation today would disable or destroy a quarter of the thousands of satellites in orbit is an open question. However, a single nuclear weapon could debilitate one or more megaconstellations. John Plumb, Assistant Secretary of Defense for Space Policy, informed Congress in May 2024 that “[s]everal analysts do believe that detonation in space at the right magnitude in the right location could render low-Earth orbit, for example, unusable for some period of time.” In answering a follow-up question, Plumb agreed that LEO could be affected for a year.
Regulating ASATs and Weapons in Orbit
While there is no general prohibition of ASATs and the Outer Space Treaty (OST) does not explicitly ban all weapons from space, Article IV does ban the deployment of nuclear weapons and weapons of mass destruction (WMD) in space or on celestial bodies, such as the Moon or asteroids.
Moreover, Article IX states that parties to the OST “shall conduct all their activities in outer space . . . with due regard to the corresponding interests of all other States Parties to the Treaty.” The indiscriminate destruction of satellites by a nuclear detonation in space would likely be viewed by most States as violating Article IX of the OST. The use of such a weapon might also violate obligations under the law of armed conflict to avoid the indiscriminate destruction of civilian objects as well as damage and destruction of civilian objects that is disproportionate to the expected military advantage.
In addition, although Russia revoked its ratification of the Comprehensive Test Ban Treaty, it is still bound by the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water (also known as the Limited Test Ban Treaty or LTBT). Article 1 of the LTBT obligates the parties to undertake “to prohibit, to prevent, and not to carry out any nuclear weapon test explosion, or any other nuclear explosion, at any place under its jurisdiction or control . . . in the atmosphere; beyond its limits, including outer space; or under water, including territorial waters or high seas . . . .” Commentary in the Woomera Manual on the International Law of Military Space Activities and Operations notes that “[a]lthough the [LTBT] is often referred to as a ‘test ban’ treaty . . . the treaty [actually] prohibits all nuclear explosions in space, regardless of their avowed or real purpose, type, or motive” (p. 80). (Disclosure: I was a “core expert” in the Woomera Manual drafting process.)
The use of a nuclear ASAT might also be a violation of the Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques (ENMOD), to which both the United States and Russia are parties. Article I states in part “[e]ach State Party to this Convention undertakes not to engage in military or any other hostile use of environmental modification techniques having widespread, long-lasting or severe effects as the means of destruction, damage or injury to any other State Party.” Article II defines “environmental modification techniques” to mean “any technique for changing—through the deliberate manipulation of natural processes—the dynamics, composition or structure of the earth, including its biota, lithosphere, hydrosphere and atmosphere, or of outer space” (emphasis added). Given that the detonation of a nuclear ASAT might severely affect LEO and the Van Allen radiation belt for a year, such an act could be a violation of ENMOD. (For further discussion of ENMOD and space activities in general, see Woomera Manual, p. 367-69.)
This is not an exhaustive list of possible violations of international legal obligations, but it does set out some of the main concerns.
The Security Council Debates
Following the flurry of speculation, allegations, and responses in February 2024, the UNSC debated the issue of weapons in space in April and May.
On April 24, the UNSC debated a proposed resolution drafted by the United States and Japan and co-sponsored by 63 countries. After preambular language that included restating obligations under Articles IV and IX of the OST, draft resolution S/2024/302 included the following in its operational section, stating that the UNSC:
1. Urges that all Member States carrying out activities in the exploration and use of outer space do so in full compliance with international law. . . .
2. Calls upon all States, in particular those with major space capabilities, to contribute actively to the objective of the peaceful use of outer space and of the prevention of an arms race in outer space and to refrain from actions contrary to that objective and to the relevant existing treaties in the interest of maintaining international peace and security and promoting international cooperation;
[. . .]
6. Recalls the obligations of States Parties under multilateral treaties related to nuclear, chemical, and biological weapons, and further calls on Member States not to develop nuclear weapons or any other kinds of weapons of mass destruction specifically designed to be placed in orbit around the Earth, or to be installed on celestial bodies, or to be stationed in outer space in any other manner[.]
Much of the text largely reiterated existing obligations under the OST, especially Articles IV and IX. However, the following week, Mallory Stewart, the U.S. Assistant Secretary of State for Arms Control, Verification, and Compliance, noted that although the OST did not prevent the development of space-based nuclear weapons and WMDs, the drafters of the resolution thought it would be “useful” to include a clause in the original text calling upon States not to develop such weapons.
During the debate, Russia and China proposed an amendment that would have added a new operative paragraph in which the UNSC would call for all States, but especially those with “major space capabilities . . . [t]o take urgent measures to prevent for all time the placement of weapons in outer space and the threat or use of force in outer space, from space against Earth and from Earth against objects in outer space. . .” and “[t]o seek through negotiations the early elaboration of appropriate reliably verifiable legally binding multilateral agreements” (S/PV.9616, p. 4).
This amendment, calling upon States to prevent the placement of any weapons and any threats of the use of force in or from space, amounts to an implicit critique of the United States’ policy of viewing space as a warfighting domain. The amendment was defeated in a vote of seven in favor (Algeria, Ecuador, China, Guyana, Mozambique, Russian Federation, and Sierra Leone), seven against (France, Japan, Malta, the Republic of Korea, Slovenia, the United Kingdom, and the United States), and one abstention (Switzerland).
In the vote on the full draft resolution (S/2024/302), thirteen States voted in favor of the original text, China abstained, and Russia exercised its veto power, blocking passage of the resolution. After the vote, the U.S. ambassador said:
Over the past few years, Russia has irresponsibly invoked dangerous nuclear rhetoric and walked away from several of its arms control obligations. It has remained unwilling to engage in substantive discussions around arms control or risk reduction. And it has defended and even enabled dangerous proliferators.
Now, Russia has vetoed a straightforward resolution that affirms a legally binding obligation under the Outer Space Treaty: that we should not be putting WMD into orbit (S/PV.9616, p. 5-6).
Russia’s ambassador responded that, inasmuch as the U.S. Ambassador “said that the failure to adopt this draft resolution does not affect Russia’s existing obligations under the 1967 Outer Space Treaty not to deploy WMDs in space,” she should “explain why the United States and Japan submitted this draft resolution in the first place, if it has no impact” (S/PV.9616, p. 10). The United States had said in its preceding statement that “in no way does this vote undermine the obligations that Russia, or any other State party, continues to have under the Outer Space Treaty” (S/PV.9616, p. 6). This could be taken to mean that Russia’s veto of the resolution did not affect existing legal obligations, not that the resolution merely restated existing obligations. The United States had earlier noted in its opening statement that the resolution “calls on States Members of the United Nations to not develop any nuclear weapons or other weapons of mass destruction (WMD) that are specifically deigned to be place[d] in orbit around Earth” (S/PV.9616, p. 2).
In any case, the Russian Ambassador continued:
We are also in favour of banning the use of force or the threat of the use of force in outer space, from outer space or against outer space. The problem is that our Western partners will not agree to that because they are engaged in the active military exploration of outer space. Let us not allow them to pull the wool over our eyes today, because they are not going to give up on the militarization of outer space (S/PV.9616, p. 10-11).
China’s ambassador stated that China abstained from the vote because “[t]he draft resolution that was just voted on is incomplete and unbalanced and does not reflect to the fullest extent the common interests and the shared call of the 193 Member States on the issue of outer space security” (S/PV.9616, p. 12).
While the vastness of space often leads to soaring rhetoric, the debate on April 24 was more like trench warfare, each side trying to rhetorically seize a few yards. The United States wanted to point out Russia’s apparent hypocrisy in touting initiatives to prevent an arms race in outer space when it was itself actively testing ASATs, including the development of a nuclear ASAT, in violation of numerous international commitments. Russia sought to refocus the debate not just on OST commitments, but as a broader initiative to ban any weapons in space.
Russia’s strategy might stem from what some have described as its sense of being “left behind in the race to leverage low Earth orbit for defense and commercial advantage . . . .” Russia may be attempting to shift the focus onto a broader discussion of the militarization of space in an attempt to counter the United States’ space strategy, which envisions space as a domain of possible military activities and maintains the right to use force, including via space activities, in self-defense (see the U.S. Department of Defense’s Law of War Manual § 14.10.4).
On May 16, Russia launched satellite Cosmos 2576 in a “co-planar” orbit with a U.S. government satellite. Although analysts do not think that it is a nuclear ASAT, Cosmos 2576’s orbit has an “alignment [that] allows the Russian spacecraft to monitor, track, and potentially interfere with a U.S. satellite because they are moving along the same path or plane in space.”
Four days later, on May 20, the UNSC debated a draft resolution co-sponsored by Russia, China, Belarus, North Korea, Nicaragua, and Syria. Much of the language mirrored, or had only slight adjustments to, the text of the previous resolution drafted by the United States and Japan. But there was one significant difference: an additional operative paragraph with the same language as the amendment previously proposed by Russia and China—and rejected by the UNSC—in the debate over the previous resolution.
The United States criticized Russia for “seek[ing] to distract global attention from its development of a new satellite carrying a nuclear device” (S/PV.9630, p. 3). It further argued that,
by seeking to use this draft resolution to put forward language on other topics that Russia knows does not have consensus support in the Council, Russia’s text also distracts from affirming the important obligations of all 116 States parties to the Outer Space Treaty, including that no nuclear weapons or other WMDs be put into orbit.
Other States, such as the Republic of Korea, the United Kingdom, and Malta also noted the lack of consensus on the additional paragraph prohibiting any weapons in space. The Republic of Korea said that, “[g]iven the dual-use nature of many space systems, it is very difficult to define a weapon in space, and it is also difficult to verify compliance, even with a legally binding agreement. Ambiguity could lead to legal divergences and open the door to the intentional evasion of legal obligations” (S/PV.9630, p. 5).
The United Kingdom framed the current debate in light of Russia’s “recent track record”:
plans to withdraw ratification of the Comprehensive Nuclear-Test-Ban Treaty, withdrawal from the Treaty on Open Skies and the comprehensive forces in Europe treaties, suspending participation in the New START Treaty, violating the Intermediate-Range Nuclear Forces Treaty and the Chemical Weapons Convention and, of course, breaching the Council’s resolutions on Iran and Democratic People’s Republic of Korea (S/PV.9630, p. 7).
The resulting vote for this draft resolution was exactly the same as the vote defeating the Russian and Chinese amendment to the previous resolution: seven in favor (Algeria, Ecuador, China, Guyana, Mozambique, Russian Federation, and Sierra Leone); seven against (France, Japan, Malta, the Republic of Korea, Slovenia, the United Kingdom, and the United States); and one abstention (Switzerland). Russia described the vote as evidence that “Western countries are now essentially isolated in the Council, and that is symptomatic” (S/PV.9630, p. 10).
China stated that:
A certain country has defined outer space as a “war-fighting domain”, accelerated the buildup of its space force and deployed anti-missile systems and offensive weapons in outer space. Although not explicitly prohibited by the Outer Space Treaty, such acts exacerbate risks of conflict in outer space, clearly violate the principle of the peaceful use of outer space established by the Treaty and run counter to the international community’s goal of upholding security in outer space and advancing the cause of its peaceful use (S/PV.9630, p. 11).
China also said that a prohibition of any type of weapons in space “received support from more than two thirds of United Nations States Members at the General Assembly, hence capturing the widespread concerns and voices of the international community, and of developing countries in particular” (S/PV.9630, p. 11).
Legal Rhetoric, Competitive Interpretation, and Military Space Activities
Although analysts do not believe Russia has placed a nuclear ASAT in space as of yet, Russia’s interest in developing this technology is an important turn of events. Once a peer, or ahead of the United States in space activities, Russia likely now sees a United States that has moved ahead of it in its use of LEO for military and commercial purposes. However, Russia may have also concluded that the United States has become reliant on space assets for both its economy and its security. According to the Union of Concerned Scientists, as of May 1, 2023, the United States had 5,184 operational satellites, Russia had 181, and China had 628. Most of the U.S. satellites are in the Starlink megaconstellation.
Yet the disparity runs deeper. Totaling both governmental and private launches, in the first half of 2024 the United States had 73 launches in comparison to Russia’s eight launches and China’s 30. Of the United States’ satellites, 4,741 were commercial satellites, 167 were governmental, 246 were military, and 30 were other civil satellites. Although the majority of U.S. satellites are commercially owned and operated, the U.S. government, including the military, is able to contract for services from various U.S. companies that provide, for example, telecommunications and Earth imaging. In the coming years, these U.S. commercial and governmental satellite systems will be increasingly in resilient megaconstellations, like Starlink. For example, the Department of Defense is also building its own megaconstellation, the Proliferated Warfighter Space Architecture.
Russia’s space strategy seems to emphasize denial of the United States’ use of space assets. The development of Russia’s ASAT capabilities and how it deploys legal arguments can be thought of as two routes toward the same goal of neutralizing the United States’ comparative advantage in space activities. Through the UN’s Committee on Disarmament and through the recent UNSC debates, Russia has tried to build support for developing international rules that prohibit the placement of any weapons in space and also prohibiting the use of force in, through, or from space. Such a rule could potentially undercut the United States’ strategic use of space assets. However, Russia has shown little interest in fostering rules regarding the regulation of ASATs, as ASATs are critical to its own strategy. Moreover, Russia maintains a rhetoric of supporting international law while seemingly developing a nuclear weapon for deployment in space. The United States can point out these contradictions, but doing so is unlikely to yield any significant changes in the diplomatic landscape.
While Russia is, on the one hand, trying to make many uses of space by the military illegal, it is also supporting a broad interpretation of rules concerning the targeting of satellites. These are both parts of a single strategy of impeding the United States from using space assets. In 2022, Konstantin Vorontsov, a deputy director of Russia’s Ministry of Foreign Affairs, warned that using commercial megaconstellations could lead to those satellites becoming legitimate targets:
We would like to specifically stress an extremely dangerous trend that goes beyond the harmless use of outer space technologies and has become apparent during the latest developments in Ukraine. Namely, the use by the United States and its allies of civilian, including commercial, infrastructure elements in outer space for military purposes. Apparently, these States do not realise that such actions in fact constitute indirect participation in military conflicts. Quasi-civilian infrastructure may become a legitimate target for retaliation. Western actions needlessly put at risk the sustainability of peaceful space activities, as well as numerous social and economic processes on Earth that affect the well-being of people, first of all in developing countries. At the very least, this provocative use of civilian satellites is questionable under the Outer Space Treaty, which only provides for the peaceful use of outer space, and must be strongly condemned by the international community.
Additional Protocol I to the Geneva Conventions (AP I) provides that civilian objects can become military objectives, and thus targetable, if “by their nature, location, purpose or use [they] make an effective contribution to military action and [their] total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage” (art. 52(2)). However, as explained in the Woomera Manual (p. 321):
[A] satellite that provides both military and civilian communications would be a military objective (and thus targetable) if its military use or purpose meets the test stated in this Rule [essentially the test from Article 52 of AP I], despite the civilian functions it may also perform. Even so, the targeting of space systems is always subject to other rules applicable to attacks, such as the prohibition on indiscriminate attacks and compliance with proportionality requirements . . . and precautions in attack . . . which regulate the manner of attack, or which may effectively prohibit an attack at all.
In its 2022 statement, Russia did not emphasize these limits. Then again, without much of a commercial space sector of its own, Russia has relatively little concern in arguing for a low bar in making commercial satellites targetable.
Also noteworthy is the final sentence in Russia’s statement, concluding that the use of civilian satellites is “[a]t the very least . . . questionable under the Outer Space Treaty, which only provides for the peaceful use of outer space, and must be strongly condemned by the international community.” Only two sections of the OST contain the phrase “peaceful purposes”: the preamble and Article IV (the latter uses “peaceful purposes” in the context of prohibiting military bases on celestial objects, which is not relevant to the issue at hand). The preamble states: “Recognizing the common interest of all mankind in the progress of the exploration and use of outer space for peaceful purposes . . . .”
Although preambular language typically does not impose legal obligations, it does provide context for the interpretation of the rest of the treaty. Accordingly, the term “peaceful purposes” has been interpreted by the United States and others as meaning non-aggressive uses of space, similar to the use of the high seas or Antarctica. As the U.S. Department of Defense’s Law of War Manual explains in § 14.10.4:
The United States has interpreted use of outer space for “peaceful purposes” to mean “non-aggressive and beneficial” purposes consistent with the Charter of the United Nations and other international law. This interpretation of “peaceful purposes” is similar to the interpretation given to the reservation of the high seas for “peaceful purposes” in the [Law of the Sea] Convention.
Concluding Thoughts
The issues of ASATs and weapons in space fall in the overlap of what is covered by “space treaties,” arms control regimes, and the law of armed conflict. The law governing activities in space paints in broad strokes, leaving details to later negotiations. The United States has been encouraging coordinated interpretation of the non-military aspects of the OST and other treaties through the statements contained in the Artemis Accords. Russia also seeks to establish interpretations of international law that support its own strategic objectives.
Beyond just the issue of military space activities, it is well-known that Russia’s use of the language and rhetoric of international law ranges from the instrumental to the cynical. In this case, Russia seems to be trying to deter the development of military and dual-use space assets by the United States while simultaneously developing its own space-based weapons, possibly including a prohibited orbital nuclear weapon that could be effective against megaconstellations. Perhaps, in space, no one can hear you dissemble.
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Christopher J. Borgen is Professor of Law and Co-Director of the Center for International and Comparative Law at St. John’s University School of Law in New York City.
Photo credit: Pexels
