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A simulation of the intercept of the Cosmos 1408 satellite by a Russian ASAT missile in a November 15, 2021 test. (credit: COMSPOC)

Arms control in outer space won’t work

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It was early evening in Washington on January 11, 2007, when an SC-19 ballistic missile took off from the Sichuan province in the People's Republic of China.[1] The missile climbed 860 kilometers before releasing a 600-kilogram payload that slammed into the defunct Chinese FengYun 1C weather satellite.[2] The test generated an estimated 35,000 pieces of orbital debris spanning 3,540 vertical kilometers, the largest debris-creating event to date that would threaten private, civil, and international assets in space, including the International Space Station.[3]

Attempts at comprehensive ASAT arms control are a waste of time. Energy is better spent pursuing narrower, more effective bans on debris-creating, kinetic ASAT tests and norms of behavior in outer space.

It was the first such test since 1985, when the United States shot down an American satellite using a direct-ascent air-launched missile. The Chinese test represented a turning point for the outer space domain, a revitalization in the struggle for outer space supremacy and the rise of a new threat to stability: anti-satellite (ASAT) weaponry. To American policymakers watching in dismay, the violent disassembly of FengYun 1C made two things clear. First, American satellites were vulnerable to attack from its largest foreign competitor. Second, in a domain devoid of rules and regulations, anything goes.

Perhaps the largest effect of the 2007 test was the urgency it gave to the outer space arms control cause. Here was the clearest demonstration that unregulated outer space was in need of better rules. Arms control in outer space, it was said, could prevent the next disaster.[4]

It was not to be. In the 15 years since China’s ASAT test, remarkably little progress has been made towards outer space arms control. One year after the 2007 test, China and Russia jointly proposed the Treaty on Prevention of the Placement of Weapons in Outer Space and of the Threat or Use of Force against Outer Space Objects, or PPWT for short, at the 2008 Conference on Disarmament. The draft treaty has floated in purgatory since its proposal, condemned to irrelevance in the face of staunch American opposition. But it remains the front runner for arms control treaties of its kind given a notable lack of proposed alternatives.

The PPWT’s fate is representative of the impossibility of codifying comprehensive arms control for outer space. Despite the legitimate threat of ASAT weapons, arms control agreements that would prevent their proliferation, restrict their use, and block their development remain out of reach. Difficulties defining ASATs, attributing their use, and verifying compliance make efforts to codify comprehensive ASAT arms control fruitless. What’s worse, arms control agreements such as these could degrade American competitiveness in space.

Attempts at comprehensive ASAT arms control are a waste of time. Energy is better spent pursuing narrower, more effective bans on debris-creating, kinetic ASAT tests and norms of behavior in outer space that could make outer space more stable and sustainable over the long-term.

Elusive definitions

Treaties that ban or control weapons must define what, exactly, they aim to ban or control. Without an ASAT definition that is simultaneously inclusive and precise, international regimes preventing the development, deployment, and use of ASATs are ineffective. Two obstacles make constructing a useful definition nearly impossible: weaponry diversity and the dual-use problem.

By the most literal interpretation of this PPWT language, almost everything can be classified as an ASAT and cannot be put into space.

The variety of potential ASAT weaponry presents a problem. ASAT weapons are any technology that can temporarily or permanently disable or destroy a satellite’s functionality. This means lasers and other directed energy weapons, air- and land-launched kinetic missiles, cyber uplink and downlink attacks, radiofrequency jamming attacks, attacks on ground stations, and maneuverable attack satellites are all ASAT weapons.

The diversity of ASAT weapons makes articulating a sufficiently comprehensive and precise definition impossible. Any attempt to do so will inevitably leave significant loopholes because each technology exists in a separate domain defined by unique operational requirements, norms, and expectations that require specific rules and regulations to control.

Controlling these technologies is especially difficult given most have legitimate, peaceful, or commonplace uses. Satellites are fragile. It takes little force to render them temporarily or permanently ineffective. When a target is defined by fragility, everything becomes a weapon, meaning innocent and commonplace technologies can be weaponized. Remotely operated repair satellites, for instance, are being developed to revitalize failing satellites.[5] But the same capabilities used to repair can be repurposed to destroy. Similarly, any satellite equipped with a radiofrequency antenna necessary to receive signals can also emit them with sufficient strength to jam the communications of nearby satellites.[6] This dual-use problem presents an obstacle for ASAT arms control by pitting legitimate and peaceful operational freedom against national security.

The PPWT defines a weapon as “any outer space object or its component produced or converted to eliminate, damage or disrupt normal functioning of objects in outer space.”[7] But by the most literal interpretation of this language, almost everything can be classified as an ASAT and cannot be put into space. The PPWT does not even attempt to address ASAT weapons that are deployed from the ground. Effective definitions elude the PPWT and will also elude future arms control attempts.

Verification problems

To identify and differentiate between compliance and disobedience, the international community must be able to identify and characterize objects in orbit. International arms control treaties cannot rely on goodwill alone. Verification capabilities must therefore be an inherent part of any agreement that restricts the use or deployment of weaponry.

But it won’t be in outer space—no reliable verification capabilities currently exist. Once an asset is deployed in orbit, it’s remarkably difficult to tell what it is and what it is capable of doing. For non-physical weapons, like cyber and jamming capabilities, there are no means to verify compliance. Any attempt to ban non-physical ASAT weapons would rely exclusively on trust. The PPWT seeks to bar signatories from placing “any weapons in outer space.”[8] It’s mere finger-wagging more than an enforceable rule without a means to verify compliance.

Effective verification mechanisms would be costly, complicated, and ineffective. And without verification capabilities, useful arms control agreements are hopeless.

Advocates for ASAT arms control would disagree, pointing to modern space situational awareness capabilities that can detect space launches and track the orbital inclination of their payloads through space-based infrared and infrasound monitoring systems.[9] Even if states can track objects that are placed into orbit, “verifying the function of a particular space object already in orbit is significantly more difficult.”[10] The “PAXSAT A” study demonstrated that uncovering the functionality of satellites in orbit is possible by utilizing a four-satellite constellation.[11] But this investigation method relies on the ability of the constellation to position itself near the object in question and the assumption that form follows function. Two problems are presented here. First, we do not have the infrastructure to conduct on-orbit investigations. Second, the logic that form follows function is fallible. Because space launches are expensive, advocates argue that the extra weight and cost needed to obscure the true function of an ASAT weapon in orbit with facade architecture is too expensive to be realistic. But basing arms control agreements on the predicted frugality of nation-states seems illogical, at best.

Even with perfect launch monitoring capabilities, significant unknowns remain. Many space-related armaments are ground-based, meaning these weapons can be developed and deployed outside of the scope of current ASAT monitoring systems. Also, for non-physical weapons, verification is simply impossible. No mechanism exists, for example, to verify compliance with moratoriums against developing or deploying cyberweapons or jamming capabilities.

In short, effective verification mechanisms would be costly, complicated, and ineffective. And without verification capabilities, useful arms control agreements are hopeless.

Attribution problems

Attribution, the ability to identify a violation and legitimately tie it to an actor, is a key ingredient of arms control agreements. The ability to attribute violations is key to justifying the invoking of punishments in accordance with international treaty law. Thus, attribution capabilities are the foundation of a deterrence mechanism that makes arms control agreements attractive and practical.

Attribution capabilities, or the lack thereof, present another problem for ASAT arms control. Some forms of ASAT attacks are attributable. Others are not. Non-physical threats, for instance, are particularly difficult to tie actions to national actors.

In the event a laser, for example, is used against a space asset, satellite operators would have a difficult time identifying the actor responsible for the attack. In the harsh environment of space, systems frequently fail without explanation. Unless the targeted satellite is equipped with sensors that could identify “a spike in thermal energy or sudden saturation of optical sensors,” there is no way to differentiate between a random satellite failure and a malicious laser attack.[12] And even if such capabilities exist, there is no guarantee one could attribute the laser’s use to a national actor.

Russia and China proposed the PPWT specifically because it satisfies the political hunger for ASAT arms control while permitting loopholes for a variety of ASAT possessions.

Jamming attacks are similarly difficult to attribute. Satellites use a narrow range of the electromagnetic spectrum to communicate. The crowded nature of orbits today means it is common for multiple space assets to use similar or identical frequencies and, as a result, routinely unintentionally jam the communications of a neighboring satellite.[13] Differentiating between intentional and unintentional jamming is difficult, if not impossible. In this environment, verification and compliance mechanisms are complicated to construct.

Recent cyberattacks have laid bare the difficult, lengthy, and uncertain process of attributing, much less identifying and understanding, cyber incursions. The Russian SolarWinds hack demonstrated a lack of an ability to definitively identify the scope and duration of a cyber penetration.[14] Similar problems will plague efforts to assert arms control regimes on cyber ASAT weapons.

Adversarial interests

International participation is another key ingredient of effective ASAT arms control regimes. But many of America’s key space-capable competitors perceive ASAT weapon possession as a strategic necessity. In other words, the interests of America’s rivals decrease the likelihood of reaching an international consensus on an anti-ASAT treaty, which is a necessary ingredient for a successful ASAT arms control regime. The United States relies on its space assets for a “diverse array of political, military and economic activities” fundamental to its national security.[15] This overreliance is seen as a weakness, something America’s adversaries can reliably exploit when conventional American military capabilities outstrip theirs.

Mutual weakness is a source of stability. American competitors, notably China and Russia, enjoy having ASATs because this allows them to exploit a major American weakness. Russia and China proposed the PPWT specifically because it satisfies the political hunger for ASAT arms control while permitting loopholes for a variety of ASAT possessions. From the perspective of Russia and China, ASATs are an equalizer that allows them to overcome a relative conventional weaknesses. The perceived strategic value of ASAT weapons makes arms control agreements that seek to legitimately and comprehensively eliminate or reduce the ability of countries to develop and possess ASATs unlikely.

Where arms control advocates go wrong

Despite these challenges, some argue that ASAT arms control agreements are a necessary aspect of a safe, secure, and stable space environment. Advocates for arms control maintain agreements could prevent an ASAT arms race. This is wrong. Arms control agreements will do more to shape the direction of, rather than prevent, an ASAT arms race. Because any agreement will be less than comprehensive, states will seek to develop ASAT weapons that fall outside of the agreement’s jurisdiction. If the agreement bans kinetic ASAT weapons, for instance, space-capable nations will push to develop more diverse, more effective non-kinetic weapons.

In addition, any agreement will likely increase the incentives to camouflage and disguise ASAT technology, worsening a problem that the arms control agreement initially set out to resolve. Any restrictions will inevitably force nations to make ASAT capabilities increasingly integrated with innocent infrastructure to avoid detection, furthering the dual-use problem, seeding doubt among the reliability of routine space assets, and incentivizing the weaponization of outer space.

ASAT weapons are a legitimate threat to the global community, and the space domain could benefit from more relevant, stronger rules of the road. But the solution is not ASAT arms control.

Even worse, pursuing ASAT arms control agreements could be detrimental to the competitiveness of American assets in space. One probable response to an ASAT arms control agreement is reduced federal government’s willingness to fund improvements to the resiliency and survivability of American space constellations.[16] Maintaining American competitiveness in space necessarily entails bolstering defensive measures against hostile ASAT capabilities. But reducing, or appearing to reduce, the threat to United States space assets through arms control agreements could make it harder to convince legislators and policymakers that expensive satellite acquisitions are worth pursuing.

From any perspective, ASAT arms control is a waste of time and detrimental to American interests.

Alternative measures

Despite challenges to a comprehensive ASAT arms control regime, two near-term actions are worth pursuing to bolster the sustainability and safety of the space environment.

First, as Michael Krepon suggests, the international community should agree to a moratorium on kinetic ASAT tests that generate debris and make the space environment more dangerous to operate in for everyone.[17] Tests like these have the characteristics that make them amenable to arms control agreements. It’s clear when it happens, how it happens, and where it comes from—in other words, tests like these are straightforward to define, monitor, verify, and attribute. They also invite international agreement. Debris-generating on-orbit ASAT tests make the space environment more difficult for everyone to operate and are, therefore, against the interest of all space-faring nations.

Second, the international community should try to establish norms of behavior that dictate activity in outer space. Norms will be more useful than codified, ineffective arms control agreements. Norms are built intentionally over time through repeated action. “Norms,” explains Audrey Schaffer, “can serve to highlight abnormal behavior, enabling warning of and protection against space threats.”[18] They can’t constrain malicious action, but they can serve to flag violations and increase international clarity as to what is right and wrong in the space domain. The United States, to capitalize on the utility of norms should, first, acknowledge that norms exist and, second, build a non-binding list of norms that can be communicated to the international community. This will serve to ignite an international conversation around what is good and what is not. Already, the international community is making meaningful progress. The United Nation’s Guidelines for the Long-term Sustainability of Outer Space Activities are a good start to a solidified, articulated collection of norms. To continue progress, the UN First Committee recently approved “a new working group to develop rules of the road for military activities in space.”[19]

ASAT weapons are a legitimate threat to the global community, and the space domain could benefit from more relevant, stronger rules of the road. But the solution is not ASAT arms control. The United States and the international community generally should let the PPWT revel in irrelevance. Instead, effort would be better spent on constructing a useful and implementable ban on definable, monitorable, and verifiable kinetic ASAT tests and solidifying general norms for behavior in outer space. Comprehensive ASAT arms controls might be politically pleasant but realistically, they're practical pitfalls.


  1. U.S. Library of Congress, Congressional Research Service, China’s Anti-Satellite Weapon Test, by Shirley Kan, RS22652, 2007.
  2. T.S. Kelso, “Analysis of the 2007 Chinese ASAT Test and the Impact of its Debris on the Space Environment,” in Orbital Debris, 2007 Advanced Maui Optical and Space Surveillance Technologies Conference; Brian Weeden, “2007 Chinese Anti-Satellite Test Fact Sheet,” Secure World Foundation, updated November 23, 2010.
  3. Mark Williams Pontin, “China’s Antisatellite Missile Test: Why?” MIT Technology Review, March 8, 2007.
  4. Daryl G Kimball, “Avoiding a Space Arms Race,” Arms Control Association, April 2007.
  5. Douglas Messier, “Robotic Satellite Servicing Tech Ready for Orbital Tests, Experts Say,”, September 27, 2016.
  6. Ben Baseley-Walker and Brian Weeden, “Verification in space: theories, realities and possibilities,” in Disarmament Forum: Arms Control Verification (Geneva: United Nations Institute for Disarmament Research, 2010), 45.
  7. Ministry of Foreign Affairs of the People’s Republic of China, “Treaty on the Prevention of the Placement of Weapons in Outer Space, the Threat or Use of Force against Outer Space Objects (Draft),” reintroduced June 16, 2014.
  8. People’s Republic of China, “Treaty on the Prevention of the Placement of Weapons in Outer Space.”
  9. Baseley-Walker and Weeden, “Verification,” 40.
  10. Baseley-Walker and Weeden, “Verification,” 42.
  11. Baseley-Walker and Weeden, “Verification,” 42.
  12. Baseley-Walker and Weeden, “Verification,” 44.
  13. Baseley-Walker and Weeden, “Verification,” 45.
  14. David E Sanger, Nicole Perlroth, and Eric Schmitt, “Scope of Russian Hacking Becomes Clear: Multiple U.S. Agencies Were Hit,” The New York Times.
  15. James Black, “Our reliance on space tech means we should prepare for the worst,” DefenseNews, March 12, 2018.
  16. Colin S. Gray, “Space Arms Control: A Skeptical View,” Air University Review 37, no. 1 (1985): 81.
  17. John Klein, Understanding Space Strategy (New York: Routledge, 2019), 226.
  18. Audrey M Schaffer, “The Role of Space Norms in Protection and Defense,” Joint Force Quarterly 87 (October 2017): 88-92.
  19. Theresa Hitchens, “UN Committee Votes ‘Yes’ On UK-US-Backed Space Rules Group,” BreakingDefense, November 1, 2021.

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