By Nivedita Raju and Sarah Erickson

In February 2024, United States government officialsclaimedto haveintelligencethat Russia was developing anuclearcapability intended to target satellites. This sparkedrampant speculationand concern about whether the reports indicated asignificant threat. The controversy, and a contentious process that followed in the United Nations Security Council, highlighted the urgent need to better understand the nexus between activities in outer space and nuclear weapons and to address these topics at a multilateral level.

An increasing number of state and non-state actors are involved in the operation of space systems, which provide a wide range of services, both civilian and military—including in the nuclear domain. This has major implications for stability and security, not least given the growing escalation risks at the space–nuclear nexus. However, even within multilateral processes and bodies that might appear best equipped to link the two issues, outer space and nuclear weapons tend to be examined separately. This essay briefly summarizes the potential escalation risks at the space–nuclear nexus. It then considers some of the difficulties in discussing this nexus in existing multilateral forums and suggests ways to overcome them.

The space–nuclear nexus

The 1967Outer Space Treatyestablishes a legal prohibition on placing nuclear weapons or other weapons of mass destruction (WMD) in orbit. While no state is known to have violated this prohibition so far, there are other ways in which developments in space systems and nuclear capabilities may interact to create dangerous escalation risks.

Nuclear-armed statesrely onspace systems, to varying degrees, for functions such as early warning of a missile attack; intelligence, surveillance and reconnaissance (ISR); verification under nuclear arms control agreements; relaying communications within a state’s nuclear chain of command; and positioning, navigation and timing (PNT) services, which can support precision-strike weapons and missile guidance. Space systems can therefore be considered a critical enabler and force-multiplier in military operations. Attacks on these systems can consequently undermine a state’s deterrence capabilities, constituting a fundamental national security threat and inviting an escalatory response.

The possibility of escalation is especially concerning as so-called counterspacecapabilities(capabilities designed to destroy, disable or otherwise interfere with space systems) that can hold such strategically relevant space systems under threat are being developed by several actors. Counterspace capabilities are not comprehensively banned by the current international framework governing space activities, meaning that there is noclear red lineprohibiting attacks on space systems that enable nuclear missions. However, the doctrines of some nuclear-armed states open the door for nuclear use to be considered as a response to such an attack. The strategic ambiguity around such attacks, or even the threat of them, contributes directly to the potential for escalation at the space–nuclear nexus.

The situation is complicated further by the fact that some space systems can be used to enable both nuclear and non-nuclear missions. This phenomenon is referred to as a form ofentanglementby some experts. For example, if a state’s early-warning satellites are attacked during a conventional confrontation, this could harm not only its ability to defend against conventionally armed missiles but also its defence against nuclear missiles. Thus, the state may respond as if the attack had targeted its nuclear capabilities, regardless of the attacker’s intent. Depending on the scenario, a state could also knowingly attack a space system and assume that any escalatory response would be limited to conventional weapons, which may not be the case.

The ‘hard’ security concerns related to the space–nuclear nexus also need to be balanced against the many beneficial, often essential, economic, social and environmental functions that space systems serve. Any negotiations towards a risk-reduction framework related to the space–nuclear nexus need to take into account preventing or minimizing negative impacts on these peaceful functions.

For all these reasons, shared understanding on the space–nuclear nexus, particularly escalation risks and how to reduce them, is essential for the future of global security.

The state of multilateral deliberations on nuclear weapons and space security

In response to the US claims about a Russian nuclear anti-satellite capability discussed above, the UN Security Council convened in April 2024 to vote on adraft resolutionjointly proposed by Japan and the USA. The draft not only reaffirmed the Outer Space Treaty prohibition on nuclear weapons in space, but also called on states to refrain from developing WMD designed to be placed in orbit or stationed in space in any manner. China and Russia then introduced anamendmentthat significantly expanded the scope, committing states to ‘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 to negotiate legally binding instruments to that effect. The amendment was not adopted, and Russia exercised its veto power to reject the original proposed resolution, arguing that the resolution was not a balanced approach to space security.

In May, China and Russia then introduced their owndraft resolution. This included language on prohibiting the development of WMD designed for deployment in space as well as language similar to their proposed amendment. This draft fell short of the required number of votes to pass.

The Security Council’s failure to adopt either resolution and the fact that it is not an inclusive negotiating body strongly suggest that it is not the best body to tackle the growing challenges of the space–nuclear nexus at the multilateral level, despite its broad security mandate. A number of other UN processes and forums currently discuss governance of the space or nuclear domains, and sometimes both. Yet in practice, none have thus far addressed the space–nuclear nexus, and none have shown themselves to be particularly well equipped to deal with cross-domain issues.

Three UN bodies might at first sight look like good candidates: theConference on Disarmament(CD), the UN Disarmament Commission and the UN General Assembly’s First Committee. All convene annually. The CD has several agenda items, including on ‘prevention of nuclear war, including all related matters’ and ‘prevention of an arms race in outer space’ (PAROS). However, despite someminimal progressthis year, the CD has beendeadlockedfor many years due to geopolitical divisions and disagreements over agenda priorities and procedural rules. Introducing new themes may thus be premature. The UN Disarmament Commission has a general mandate to discuss disarmament questions and in 2023 deliberatedtransparency and confidence-building measures (TCBMs) in outer space. The First Committee also holds general thematic debates on nuclear weapons, other WMD and space, among other topics. However, both the Disarmament Commission and the First Committee have limited capacity for detailed discussion on cross-domain issues. Furthermore, the First Committee is dominated by national statements and prioritizes work on adopting resolutions and decisions.

Thus, none of the three forums could easily hold substantive discussion on risks at the space–nuclear nexus, a nascent topic that at this stage requires more informal and interactive exchange. Increasing the capacity of states to engage on these matters is a prerequisite to pursuing convergence towards the drafting of resolutions and negotiations of treaties meant for those forums.

For space governance, theCommittee on the Peaceful Uses of Outer Space(COPUOS) covers issues pertaining to the exploration and use of outer space for peaceful purposes, but explicit security-focused items are not included in its agenda of work.

There isno comprehensive established regimeto discuss security matters in outer space nor is there a review conference or annual meeting focusing on implementation of the Outer Space Treaty. Due to this gap, various time-bound processes have been initiated dedicated to space security—for example, the2019 UN Group of Governmental Experts(GGE) on further practical measures on PAROS, the2023 Open-ended Working Group(OEWG) on reducing space threats through norms, rules and principles of responsible behaviours, and the2024 GGEon further practical measures on PAROS. Their results have been mixed, depending on the political will and constructive engagement of participants. For example, of the three, only the 2024 GGE was able to adopt aconsensus report.

For nuclear issues, the UN has mandated review conferences and preparatory committees under the 1968Treaty on the Non-Proliferation of Nuclear Weapons(NPT) and meetings of states parties for the 2017Treaty on the Prohibition of Nuclear Weapons(TPNW). These regimes allow states to regularly consider nuclear non-proliferation, disarmament and peaceful uses of nuclear energy. Yet the meetings associated with these regimes centre on treaty implementation. The inability of NPT states parties to reach consensus on final documents since 2010 makes it difficult for them to consider broad developments in other domains that may impact on nuclear risk. Meanwhile, the limited membership of the TPNW, which does not include any nuclear-armed states, provides an impediment to considering space–nuclear risk in that context.

These forums also face constant challenges related to resources. Many states do not have the capacity—in terms of personnel, expertise, time or funds—to engage actively in all of them.

The limited attention paid to the space–nuclear nexus in existing multilateral forums may also be attributed to a desire by states to maintain distinct processes. Given the already challenging security landscape, adding new developments related to these topics in focused forums (whether in the space or nuclear domains) may be seen as prohibitive to achieving any results, especially in the light of the requirement for consensus in some of them and the sensitive political history between outer space, missile defenceand links to strategic stability. However, this inattention has greatly limited states’ ability to have a multilateral conversation on space–nuclear risk at all, let alone to prioritize a common nuclear risk-reduction agenda involving outer space.

Creating multilateral spaces to discuss risks at the space–nuclear nexus

How might states and other actors help to facilitate discussion of escalation risks at the intersection of space and nuclear issues? Below are three suggested starting points.

Raise the space–nuclear nexus in ad hoc space security processes

In 2023 the UN General Assembly adopted two resolutions establishing new OEWGs: one on further practical measures on PAROS (resolution78/238) and one on reducing space threats through norms, rules and principles of responsible behaviours (resolution78/20). These are due to convene soon, although the General Assembly will shortly decide whether to merge the two. With enough shared interest among a coalition of states, the space–nuclear nexus could be included as a topic area for consideration in such processes, as was done for other topics in the OEWG on reducing space threats—for example, ‘protecting critical space-based services to civilians as well as services that support humanitarian operations’.

Even if there is no direct language on an issue in the mandate of a process or negotiating body, states have the prerogative to share their security perspectives and concerns. Therefore, a feasible and immediate step, especially considering the future OEWG(s) on space security scheduled to commence, is for states participating in such processes to bring the issue to the attention of others through working papers (possibly also through coalitions or partnerships), statements, side events and other informational activities.

Raise the space–nuclear nexus in existing nuclear processes

The NPT must be considered as a venue for space–nuclear nexus issues, despite its limitations. While it excludes nuclear-armed states (and space powers) that are not parties to the treaty, it has already managed to raise other relevant intersecting topics, such as the cyber–nuclear nexus. Thechair’s summaryof the 2024 NPT Preparatory Committee notes that some states ‘also expressed support for further work by the nuclear-weapon States on risk reduction measures, including to mitigate the potential for emerging technology, such as artificial intelligence and offensive cyber capabilities, to multiply nuclear risks’. In future NPT meetings, states could include counterspace capabilities alongside other listed emerging technologies that multiply nuclear risks.

Additionally, there is potential to discuss the space–nuclear nexus under the TPNW, given its focus on the humanitarian consequences and environmental impacts of nuclear weapon use. Yet there is less research on direct and indirect impacts of potential nuclear use in outer space. Engaging with the Scientific Advisory Group established by the TPNW would be useful in this and other ways. The group is mandated to review relevant research, including on technological developments that may have implications for nuclear risks, humanitarian consequences and nuclear disarmament overall. While research through this group may be limited to the TPNW states parties, it would nonetheless drive engagement, particularly in developing research agendas and related mandates on the space–nuclear nexus.

Increase cross-cutting engagement on the nexus, in both formal and informal processes

In order to have meaningful and productive multilateral debate, states need to be well informed about the escalation risks, as well as the potential humanitarian and environmental ramifications of developments at the space–nuclear nexus. The 2002Hague Code of Conduct against Ballistic Missile Proliferation(HCOC) can strengthen understanding of the space–nuclear nexus by encouraging discussions during its annual Regular Meetings.While it is a voluntary instrument and not all states are subscribing parties, the HCOC is particularly relevant to the space–nuclear nexus, as it considersboth domains. Under the HCOC, states commit to providing others with notifications ahead of launching either ballistic missiles (capable of delivering WMD) and space-launch vehicles, or test flights of either, along with annual reports on their relevant policies.

Outside governmental processes, there is additionally a role for experts and civil society in building up relevant knowledge and raising global awareness. Facilitating dialogue bycreating spacesoutside official forums where the space and nuclear communities, including those in civil society, can exchange views and knowledge is vital. Also important isregion-specific dialogue, as nuclear risks differ between contexts. Policy communities can encourage these efforts and, as appropriate, actively engage with them.

Ultimately, attacks on space systems may trigger or fuel escalation towards nuclear use, which would have devastating consequences for all. It is critical to address the space–nuclear nexus at the multilateral level.

About the authors:

• Nivedita Rajuisa Researcher inthe SIPRIWeapons of Mass Destruction Programme.
• Sarah Ericksonis a Research Assistant with the Space Security and WMD programmes of the United Nations Institute for Disarmament Research (UNIDIR).

Source: This article was published by SIPRI