Today, more nations than ever are contributing to and benefiting from the exploration and use of outer space. In the past five years alone, more satellites have been launched by governments and commercial companies than in the previous six decades combined. More than 100 nations and multilateral organisations now have at least one satellite in orbit, compared to just 14 at the turn of the century. There are now more than 10,000 active satellites, including for critical defence and national security functions, with more than 40,000 objects including debris currently in orbit—a serious challenge for ad hoc space traffic management. Safeguarding the space environment and the significant positive benefits derived from it now constitutes one of the principal challenges of the 21st century.

Critical military functions including early warning, crisis communication, and command-and-control systems rely heavily on space-based systems. Satellites support missile launch detection, secure communications, navigation, and intelligence—all functions critical to avoiding miscalculation and unintended escalation. As space becomes more congested, contested, and militarised, interference with these systems, whether deliberate or accidental, has the potential to magnify the risk of crisis instability, particularly in the nuclear domain.

The space domain described above looks completely different today than that which existed when the 1967 Outer Space Treaty—officially the “Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies”—was established as a foundation for international law governing the use of outer space. The Treaty’s legally-binding commitment to not place in orbit any objects carrying nuclear weapons or any other kinds of weapons of mass destruction remains essential. Increasing confidence in states’ adherence to this prohibition should be a priority. Yet the security challenges presented by the increasing use of space for military and civilian uses—including dual-use systems as we have seen throughout the war in Ukraine—cannot reasonably be met by relying only on a treaty designed almost 60 years ago.

Without practical steps to prevent conflict in space, the danger of nuclear catastrophe—by design or by blunder—grows significantly. The risk is further exacerbated by uncertainty over the future of nuclear arms control, allegations of plans to place nuclear weapons in space, and the possibility that one or more nuclear-armed states may resume explosive nuclear weapon tests. In such an environment, instability in space may trigger or accelerate a crisis on earth.

In January 2022, the leaders of China, France, Russia, the United Kingdom, and the United States together affirmed that, “a nuclear war cannot be won and must never be fought” and that strategic risk reduction was among their foremost responsibilities. These vital principles are essential to ensuring predictability, building trust, and reducing the danger of nuclear war. Fulfilling this responsibility today requires urgent attention to a domain that has become indispensable to nuclear stability: outer space.

Since the early 1960s, the United Nations has passed a series of resolutions, and nations have concluded various agreements, containing principles and obligations governing the peaceful exploration and use of outer space. Today, those principles must be applied in an era of rapid technological development, including cyber and artificial intelligence, and the expanding military use of space including dual-use systems by a growing number of nations. Simulated and actual testing of anti-satellite weapons by several nations have demonstrated how space could become a battlefield, in some cases creating dangerous debris in space. Even the legally binding commitment under the 1967 Outer Space Treaty regarding weapons of mass destruction appears at risk. Any use of nuclear weapons in outer space would render important regions of space unusable for extended periods causing indiscriminate and devastating impacts for everyone on earth.

Leaders of nuclear-armed nations and other states parties to the Outer Space Treaty, many of whom possess or could develop capabilities to disrupt the peaceful use of space, should affirm the historic principles governing the use of outer space for peaceful purposes, and—recognizing that space is now a contested domain—commit to apply and adapt these principles to reducing the risks of conflict in space. Such a statement would signal a shared recognition of responsibility to prevent war in space, lay the groundwork for practical steps to reduce risks (including measures governing the testing and deployment of anti-satellite and other space weapons), and help ensure that space remains regulated and free. These principles could include the following seven points:

1. The importance of international cooperation in the peaceful exploration and use of outer space, for the benefit of all peoples.
2. The importance of freedom of scientific investigation in outer space.
3. The importance of ensuring that space remain free from claims of sovereignty or occupation, and that the moon and other celestial bodies be used exclusively for peaceful purposes.
4. The importance of further developing the rule of law and non-binding norms of behaviour in the exploration and use of outer space. Such a framework could be applied to international space traffic management, broader transparency and confidence building measures applied to anti-satellite weapons and testing, and avoidance of unintended escalation especially associated with dual-use systems.
5. The importance of refraining from placing in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, installing such weapons on celestial bodies, or stationing such weapons in outer space. Nuclear weapons in space would increase the risk of unintended, mistaken, or unauthorised nuclear use and put increasing pressure on nuclear “fail-safe” measures designed to reduce these risks. Here, too, both normative and legally binding measures building on the Outer Space Treaty should be considered and applied.
6. The importance of states bearing international responsibility for national activities in outer space, whether conducted by governmental agencies or non-governmental entities, including the commercial sector.
7. The importance of consultations regarding activities or experiments that could interfere with the peaceful exploration and use of outer space.

Development and acceptance of these principles should be facilitated by a strong new impulse to inclusive dialogue on space security and stability mandated by political leaders. Leaders should make clear their intent to establish a process capable of responding more rapidly to changing technological, political, and military developments in the space domain.

The dialogue would build on existing treaties and agreements, take advantage of existing forums where possible, and support concrete steps in support of the above principles. If a new forum is required, the three depositary governments of the Outer Space Treaty—the Russian Federation, United Kingdom, and the United States—working with, among others, China, the European Union, India, Japan, France, Germany, and the United Nations, should undertake to organize such a dialogue, including participation by the commercial sector, and prepare an agenda for its first meeting at the earliest possible date.

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The European Leadership Network itself as an institution holds no formal policy positions. The opinions articulated in this group statement represent the views of the author rather than the European Leadership Network or its members. The ELN aims to encourage debates that will help develop Europe’s capacity to address the pressing foreign, defence, and security policy challenges of our time, to further its charitable purposes.