Debris-Creating Anti-Satellite Tests Score Low on Strategy and Military Benefits
There are more than 1.2 million pieces of space debris larger than one centimeter in orbit today; under the right circumstances, any of them could cause catastrophic damage to a nation’s space economy, its communications technology, and even its nuclear command and control infrastructure. And yet, the amount of debris in space is increasing rapidly, while countries continue to scale up their space programs.
An outsized amount of trackable space debris can be attributed to a relatively small number of low-frequency, yet extremely high-consequence events: instances of states shooting down their own satellites. These direct-ascent anti-satellite (DA-ASAT) tests, as they are known, have been conducted by the United States, Russia, China, and India, and are designed to test these countries’ abilities to destroy their adversaries’ satellites during wartime. Past tests have created space debris, increasing risks of collision and potential damage to other states’ satellites. There is shared recognition of the risks posed by space debris and such debris-generating tests. Debates on debris-creating DA-ASAT tests were prominent in the most recent session of UN space security talks in July. While exchanges were relatively more constructive than previous sessions, long-standing divisions reigned over what types of capabilities to regulate, how to verify them, and where to start. Some continued to advocate for a ban on debris-creating (‘destructive’) DA-ASAT tests, even suggesting a legally-binding ban, while others argued that focus on testing was too narrow and did not cover development, deployment, and use, or other capabilities of concern such as space-based weapons.
States’ views on missile defense have largely contributed to these debates, posing significant challenges to concrete de-escalation measures on multilateral or bilateral bases. Given the strong degree of technological overlap between missile defenses and DA-ASAT, states may perceive any suggested regulation of the latter as inherently limiting the former.
These debates have not captured the limited military utility of such tests. This essay argues that despite technological overlap, there is scope to decouple missile defense from DA-ASAT technologies on the basis of the limited military utility of debris-creating tests. Accordingly, states should consider commitments to ban debris-creating tests.
Overlap between missile defense and DA-ASAT technologies
There is an immensely strong degree of overlap between the technologies underlying missile defense interceptors and DA-ASAT weapons. Both systems require the same elements–rocket motors, guidance, navigation, control systems, and a payload. In addition, the technical knowledge and industrial bases needed to build them are largely identical. As a result, a capability to develop one system constitutes a latent capability to develop the other.
Indeed, repurposing a missile defense system for a DA-ASAT strike against a satellite can be less technically challenging than a missile intercept, depending on the state’s capabilities. Two components are essential: first, that the missile defense system can deliver a sophisticated kill mechanism to a high enough altitude to reach its target. A missile capable of launching a payload to its maximum range can typically launch that same payload vertically to an altitude of about half that range. For instance, a missile carrying a kill vehicle to a maximum range of 2,000 km (1,243 miles) could potentially carry that same kill vehicle to an altitude of approximately 1,000 km (620 miles). Second, the state would require advanced space situational awareness capabilities to determine the precise orbital parameters of its target. Satellites travel on predictable, observable trajectories and have limited maneuverability, thereby making them relatively easier targets for DA-ASAT systems. In contrast, a missile intercept mission could take place at any time, and requires both a sufficient alert posture and a degree of nimbleness that are not required for a DA-ASAT mission.
Importantly, DA-ASAT missions also do not encounter discrimination challenges to nearly the same degree as missile defenses. Modern ICBMs may contain combinations of decoys (such as mylar balloons) or penetration aids (such as chaff) that are meant to confuse radars or help evade incoming interceptors. While there are certain combinations of active and passive defenses that could theoretically be built into a satellite architecture to enhance resilience against attacks, many of these concepts remain aspirational and have not yet been deployed at scale.
As a result, a state that already possesses sophisticated missile defense capabilities would be able to repurpose those same capabilities for DA-ASAT missions without significant difficulty. For states reliant on space for military and civilian missions, the rise in such capabilities and their testing poses major concerns.
Different systems for different targets
Whether a particular missile defense system can be adapted for a DA-ASAT mission depends to a large extent on the orbital band where the targeted satellites are located.
Most strategic early warning satellites are located in geostationary orbit (GEO)–at an altitude of 35,786 kilometres–and highly elliptical orbit (HEO), in which satellites spend the majority of their orbit at an apogee of similar altitude. In order to kinetically target satellites orbiting at that altitude, an interceptor would need to achieve a degree of delta-v that is simply not feasible for nearly all missile defense systems in existence today, although this will likely change as technologies evolve. Some states allege that others are pursuing DA-ASAT capabilities to target satellites in GEO, but no state has publicly acknowledged such capabilities, and there is no evidence of their operational status.
Instead, the majority of operational missile defense systems are most suited for targeting satellites in low Earth orbit (LEO), and to a lesser extent, medium Earth orbit (MEO). These orbits typically include satellites with applications for telecommunications, remote sensing, military intelligence, surveillance, and reconnaissance (ISR), and navigation (including GPS, GLONASS, Galileo, and BeiDou), among other capabilities. In most cases, a missile defense system that is designed to intercept in midcourse phase will be most appropriate for a DA-ASAT mission against satellites in these orbits, although some terminal systems may also be relevant depending on the target and context.
These systems carry kinetic kill vehicles (KKVs) that utilize hit-to-kill technology. After the missile booster reaches a high enough altitude, it releases a KKV equipped with sensors that home in on the target and destroy it using kinetic force. If the guidance systems are accurate enough, the high closing speeds of the KKVs can project significantly higher force than a blast-fragmentation warhead, rendering them unnecessary.
There are several states that possess DA-ASAT capabilities, with four having conducted destructive tests: China, India, Russia and the USA. Among the five permanent members of the UN Security Council (the five recognized nuclear-armed states under the NPT), Chinese, Russian and US missile defense systems with ASAT potential is evident.
China has multiple systems capable of targeting satellites in LEO. These include the mobile HQ-29 system, which according to a Chinese military magazine, can carry up to two interceptors and engage targets at an altitude of 2,000 kilometres–as well as the DN-3, the HQ-19, and the SC-19. The SC-19 is believed to be derived from the DF-21 MRBM, and has previously achieved intercepts at altitudes of approximately 250 kilometres (155 miles) and 865 kilometres (537 miles), the latter resulting in the destruction of an orbital target in 2007 that reportedly created over 3,500 pieces of trackable debris (see page 05-01).
Russia similarly operates several systems that could function as both upper-tier missile defense systems and anti-satellite weapons. These most notably include the Nudol, which the US Defense Intelligence Agency assesses was used to conduct a test against a defunct Russian satellite in November 2021. The US Space Command estimated the test created over 1,500 pieces of trackable space debris, while the Russian Ministry of Foreign Affairs declared that debris from the test did not create any threat.
The United States operates both the Ground-Based Midcourse Defense (GMD) system, which is designed to intercept strategic ballistic missiles while they are traveling in their midcourse phase of flight, as well as the SM-3––which was used to destroy a non-functioning reconnaissance satellite in 2008, that created approximately 175 pieces of trackable space debris.
The USA in 2025 also announced a major shift in missile defense policy, with ‘Iron Dome for America’ (later renamed ‘Golden Dome’), to defend the entire US homeland from all types of missiles from all adversaries. While this initiative aims to implement a layer of space-based interceptors, which are distinguished from DA-ASATs (as they would be space-based), it will also likely include enhancements to the ground-based interceptor force, including the SM-3. Following the announcement of Golden Dome, fears about possible tests for such systems have also been rekindled.
Notably, no state has ever used a DA-ASAT to attack another state’s satellite; this is unprecedented, would be considered a clear use of force under international law, and invite escalatory responses.
Governance and initiatives
There are currently no restraints on missile defense under bilateral or multilateral instruments. The 1972 Anti-ballistic Missile Treaty introduced certain limitations between the US and the Soviet Union, later succeeded by Russia in the treaty. Parties agreed to maintain only one strategic missile defense site with up to 100 launchers and 100 interceptor missiles, and committed not to develop, test or deploy sea-based, air-based, space-based or mobile-landed ABM systems or components. However, the US withdrew from the agreement in 2002, a move that in part has driven the expansion of missile defenses and maneuverable missiles among competitors.
US withdrawal from the ABM Treaty had ramifications on space security talks, amplifying concerns about the US pursuing space-based missile defense systems that could undermine Chinese and Russian deterrents–concerns further fuelled by USA’s Golden Dome. Under the 1967 Outer Space Treaty, placement of WMD in orbit is expressly prohibited, with no consensus on the regulation of other types of weapons. The issue of DA-ASAT testing has seen renewed interest following the rise in destructive testing. In 2022, the USA pledged to refrain from destructive DA-ASAT tests, referring to previous Chinese and Russian tests. The US commitment did not however, mention its own previous tests or India’s test in 2019. Several states made similar national pledges in the months that followed, culminating in a US-led resolution adopted by a wide majority by the UN General Assembly in 2022 to refrain from debris-creating DA-ASAT tests. Nine states abstained from voting, including India, and nine voted against, including China and Russia. The issue of DA-ASAT testing has since been raised in subsequent UN space security processes, including the July talks. These exchanges would benefit from more comprehensive inquiry into the utility of debris-creating tests.
Low military utility of DA-ASAT tests
Much has been reported on harmful effects of debris from destructive DA-ASAT tests, which directly threatens space-based assets of all actors. Debris can even interfere with crewed missions, threatening human space exploration. Even tests conducted at lower altitudes still generate debris and increase risks of collision. LEO is considerably overcrowded with debris, as well as active ‘megaconstellations’ of satellites–such as SpaceX’s Starlink–indicating significant risk of collision already.
Yet, there is less emphasis on the low military utility of these tests, both in peacetime and in times of rising tensions preceding a conflict.
First, a destructive DA-ASAT test has permanent and indiscriminate effects. Debris from the test could undermine space-based assets that enable critical conventional weapons and operations for the executing state, which would be detrimental to its own interests.
Moreover, such a test could transform adversary dynamics by affecting other actors, as there is no specific effect against a singular adversary. Even if a state is more risk-seeking and less reliant on space, it could alienate allies or strategic partners reliant on space and isolate itself politically.
Second, the attribution of such tests is also undisputed, making it clear who the executing party is, and subjecting them to political isolation. This also highlights the ineffectiveness of strategic or coercive signaling for a destructive test, because it is unlikely to influence a specific adversary’s cost-benefit calculation without also impacting other stakeholders.
Third, conducting such a test would not signal a new capability to an adversary. States are well aware of the missile defense capabilities at their adversaries’ disposal; there is thus no need for a debris-creating test to convey their effectiveness. Open-source assessments, the use of these systems in ongoing conventional combat scenarios, and public parades of missile defense systems are already creating this effect.
Fourth, kinetic tests are not needed to validate a state’s operational DA-ASAT capabilities. As already discussed, these missions are significantly easier than conducting realistic missile defense intercepts, given the predictable trajectories of satellites. As a result, states can validate their capabilities through other means, including missile defense intercept tests and simulation technologies. To put it another way, if the United States was not confident in its ability to disrupt the satellite operations of its adversaries during wartime, it almost certainly would not have issued its 2022 moratorium on destructive DA-ASAT tests. Destructive testing of these systems is not necessary.
Steps forward: Seeking bilateral and multilateral test-ban commitments
Space security talks have historically sought common understandings on DA-ASAT systems focusing on debris aspects. The low military utility of such tests should also be a factor. This would allow states to consider widening the scope of previous efforts on destructive DA-ASAT tests–possibly extending these to all debris-creating tests, including those involving co-orbital systems. This is especially relevant given US pursuit of Golden Dome and its space-based interceptor layer, which has co-orbital ASAT potential. In addition, proposals should uniformly acknowledge states that have conducted past tests. Selectively naming and shaming actors that have conducted DA-ASAT tests only further drives political agendas and reinforces divides already tangible in UN forums. A balanced approach to regulate capabilities would in turn help secure buy-in from states that are more wary of the narrow scope of previous proposals for a DA-ASAT test ban.
Given the strong degree of technological overlap between defensive interceptors and offensive DA-ASAT weapons, regulation of such systems is no small feat, particularly with arms control at a standstill. Eventually, states could consider pairing test-ban commitments with restrictions on interceptors in strategic stability talks. This could spark consideration of measures that extend to development, deployment and use. However, in the current environment of declining trust and magnifying strategic competition, banning debris-creating tests is a concrete step towards stability that favors interests of all states seeking to conduct space activities. Emphasizing the low military utility of such tests is essential for more constructive exchange.
Note: Conversions from kilometers to miles are approximate.
In the current environment of declining trust and magnifying strategic competition, banning debris-creating tests is a concrete step towards stability that favors interests of all states seeking to conduct space activities.
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