On February 15, 2024, former national security advisor Jake Sullivan briefed members of the United States (U.S.) House on alarming intelligence suggesting that Russia might be developing space weapons with nuclear capabilities. The potential for nuclear-armed space weapons could lead to a destabilizing arms race, exacerbating the already tense Russo-American relationship. This shift threatens to undermine the foundational principles of the Outer Space Treaty of 1967, which established space as a domain free from national appropriation and restricts certain military activities in space, including the establishment of military bases, fortifications, and weapons testing. To prevent this erosion of international norms, the U.S. and its spacefaring allies must move beyond rhetoric and take deliberate diplomatic steps that reinforce the Treaty’s authority. This includes using multilateral forums to build consensus around updated norms—such as prohibiting the deployment of nuclear-armed ASAT systems or setting clearer rules for satellite self-defense—and advancing UN resolutions that address emerging risks concerning weapons in orbit and the targeting of civilian satellites, while working to establish transparency and confidence-building measures with adversaries and competitors alike. Space has long been a realm of human ingenuity and exploration. The Outer Space Treaty of 1967 is the foundational agreement maintaining this peaceful frontier. Yet nearly six decades later, the growing militarization of space began to challenge the Treaty’s original spirit. Spacefaring nations have increasingly prioritized military applications of space—deploying satellites for missile warning, surveillance, and secure nuclear command and control. Countries like the U.S., Russia, China, and India have tested destructive anti-satellite (ASAT) weapons, while others are developing systems that could target or disable rival satellites. These developments are especially concerning because they endanger not only strategic stability but also the infrastructure that underpins everyday life. Satellites carry out data transmissions essential for daily activities, from GPS navigation to financial transactions. At the same time, they secure military and government communications, intelligence, and missile warnings, making them ideal targets for adversaries seeking to cause widespread disruption. What do we know about existing ASATs and nuclear-armed ASATs? The U.S., Russia, and China, among several other countries, have developed and deployed satellites for defensive military posturing including communication, navigation and reconnaissance. These satellites also serve as dual-use technologies capable of being repurposed for offensive operations, such as destroying rival satellites. On Feb 13, 2024, the House Intelligence Committee publicly released intelligence which confirmed that Russia is developing nuclear ASAT weapons designed specifically to destroy or incapacitate adversary satellites. Because ASAT capabilities primarily target satellites in orbit, Russia’s pursuit of a space-based nuclear weapon has raised urgent concerns in Washington and allied capitals, prompting renewed focus on crisis decision-making and the catastrophic risks of orbital deterrence. The Director of National Intelligence and the DIA warned that such a system could serve both as a deterrent and a tool to disable Western satellite networks. Given the indiscriminate impact of a nuclear detonation in orbit, both American and European satellites, especially those supporting NATO, are vulnerable targets. Although destructive ASAT weapons have not yet been used in warfare, Russia and the U.S. demonstrated their capability to operate these weapons by destroying their own satellites during the 16 total tests conducted since 1959. Other nuclear states, such as China, demonstrated interest in enhancing space warfare capabilities through the development of counterspace weapons. As dependence on space-based technology for essential civilian and strategic functions continues to grow, the potential threat to other countries’ satellites becomes more significant and troubling. ASAT testing also creates considerable orbital debris, further endangering both military and civilian satellites by increasing collision risk and complicating future space missions. No country has fully developed satellites armed with nuclear weapons. While Russia and the U.S. have not yet fielded nuclear-armed satellites, both have a history of deploying nuclear-powered satellites. Nuclear-powered satellites are less concerning than nuclear-armed satellites, since they would not give countries the capability to effectively attack a large number of satellites in orbit. They also do not violate existing space treaties. States can reinforce this distinction by committing to transparency around satellite payloads and clearly signifying peaceful intent. The military consequences of ASAT weapons The development and potential deployment of nuclear-capable space weapons introduces new uncertainties that could destabilize international security. Since the early 1960s, countries such as the U.S. and the Soviet Union have possessed the capability to target satellites from Earth. However, these early ASAT systems posed a more limited threat compared to space-based nuclear ASATs. Ground-based weapons, though still dangerous due to their potential to generate space debris, are generally kinetic and target-specific. Detonating a nuclear weapon in space, however, would generate intense radiation and electromagnetic effects, damaging or disabling not just the intended target but potentially dozens or even hundreds of nearby satellites. While such blasts would not create debris, they could damage electronics across wide orbital zones, consequently posing a far greater threat. It would also damage civilian satellites from any number of nations, thus indirectly making it a weapon of mass destruction, according to UN General Assembly Resolution 32/84. In response to the growing threat, U.S. defense officials, through public statements and strategic planning documents, have emphasized improving satellite resilience and coordination with allies to signal that the deployment of nuclear weapons in space will not be tolerated. To reduce vulnerability, states are already adjusting defensively to this impending reality. The U.S. began to increasingly rely on constellations of smaller satellites, which are more difficult to target by ASATs due to their low radar signatures and unpredictable flight paths that make coordinated attacks significantly more difficult. The diplomatic consequences of ASAT weapons In addition to military consequences, Russia’s deployment of a nuclear-armed ASAT weapon would carry serious diplomatic and legal ramifications. It would likely fracture already fragile cooperation between Moscow and Washington, including long-standing joint initiatives like the International Space Station (ISS), where both countries have historically collaborated despite geopolitical tensions. More broadly, it could derail multilateral forums such as the UN Committee on the Peaceful Uses of Outer Space (COPUOS) or future space traffic coordination efforts. Past incidents, such as Russia’s 2021 ASAT test that created over 1,500 pieces of debris, led to public condemnation from U.S. officials and allies, who described the act as “reckless” and “irresponsible.”The likely erosion of trust and cooperation between the two nations could signal the end of legally binding arms-limitation agreements between Moscow and Washington, particularly the New Strategic Arms Reduction Treaty (New START)—an agreement limiting strategic nuclear arsenals. The timing is especially critical given the impending expiration of the New START treaty in 2026. While the development of ASAT weapons does not directly violate New START, their deployment would further erode trust and likely eliminate any remaining will to renew or negotiate new arms control agreements. U.S. officials have already signaled diminishing confidence in bilateral arms control, and a nuclear-armed ASAT would almost certainly seal the fate of New START. From a legal perspective, such a treaty breach would weaken the international legal framework that has safeguarded space as a domain for peaceful exploration and scientific advancement for half a century. It not only threatens space security but also sets a dangerous precedent that could reverberate across global security landscapes. These concerns are magnified considering Russia’s history of withdrawing from arms-limitation agreements, such as the Open Skies Treaty and Strategic Arms Limitation Talks (SALT) Agreements. International responses to counter emerging space threats In light of these new developments in space weaponization, additional efforts have been made to reinforce the existing international norms that aim to keep space free from nuclear weapons. For instance, Japan and the U.S. spearheaded the push for General Assembly Resolution 72 (2023). This resolution called for the strengthening of international cooperation on the peaceful uses of outer space and established a working group to develop norms and confidence-building measures to prevent an arms race in space. This was one of the six resolutions adopted during the 78th session of the UN General Assembly focused on reducing threats to outer space. In April 2024, the U.S. and Japan proposed an additional resolution in the Security Council calling on all nations to commit not to place nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies, or to develop nuclear-armed ASAT systems. However, Russia vetoed the resolution due to alleged concerns over strategic imbalances. Russia asserted that the resolution was influenced by geopolitical interests rather than sincere disarmament efforts. Despite the resolution’s potential to bolster international norms and promote cooperative security measures, the veto reflects ongoing tensions and conflicting national interests that hinder the development of space security frameworks. Future Responses The signatories of the Outer Space Treaty could not have imagined the world as it is today, where international security, communication, and even our ability to tell time is space-dependent. Chief of Staff of the U.S. Space Force Chance Saltzman termed the potential launch date of Russia’s nuclear anti-satellite weapon as ‘Day Zero’ due to the impact that it could have on civilian and military structures. With reports suggesting that such a system may soon be operational, major space powers and UN Security Council members, must take coordinated steps to address the threat. Failing to act now risks crossing a threshold that would fundamentally destabilize both space and Earth-based systems. The U.S. and its allies should actively support General Assembly Resolution 231 (2023), which prohibits destructive ASAT missile testing. Diplomatic lines of effort should involve both public reaffirmations in multilateral forums and private or back-channel diplomacy to build consensus—such as privately convening key spacefaring states to draft a stronger, non-binding political code or a legally binding protocol. Because General Assembly resolutions are not subject to veto, Russia cannot formally block progress, but its resistance could still undermine consensus. To address this, states should engage Russia diplomatically, offer reciprocal transparency measures—such as satellite payload disclosures or ASAT test notifications. While these steps could build trust, they also carry intelligence or political risks, potentially drawing domestic pushback over national security concerns or perceived concessions to a geopolitical rival. These proposals will not fully eliminate the risk of space conflict, nor are they immune to shifting political winds, budgetary constraints, or verification challenges. Yet, carefully calibrated transparency paired with diplomatic pressure can serve as a vital tool in preventing escalation and preserving space as a shared domain. A bilateral U.S.–Russia agreement on ASAT testing, potentially folded into a successor to New START, could also anchor these efforts in formal arms control. The opportunity is there, but it will take coordinated political will to seize it. Our choices today will determine whether space continues to be a space of awe and possibility or becomes yet another theater for human strife. This decision should be guided by an overriding commitment to safeguarding the future of humanity.