Placement of Weapons in Outer Space: The Dichotomy Between Word and Deed

Almudena Azcárate Ortega
Thursday, January 28, 2021, 8:01 AM

Spacefaring states have claimed to support the prevention of an arms race in outer space, yet some of them have continued to develop and test counterspace capabilities, which fosters the weaponization of outer space.

A U.S. anti-satellite missile on display at the Smithsonian National Air and Space Museum (; CC BY-NC 2.0,

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The year 2020 ended with a new anti-satellite test that could be the foreteller of increasing tensions in outer space and the continuation of the space arms race. Russia conducted a test of a direct-ascent anti-satellite weapon (ASAT) on Dec. 15, which garnered the criticism of the United States: U.S. Army Gen. James Dickinson, commander of the U.S. Space Command, stated that “Russia publicly claims it is working to prevent the transformation of outer space into a battlefield, yet at the same time Moscow continues to weaponize space by developing and fielding on-orbit and ground-based capabilities that seek to exploit U.S. reliance on space-based systems.”

However, the year’s end also brought with it yet another attempt to curb the weaponization of outer space: the adoption of the Draft Resolution on Responsible Behaviours in Outer Space at the Plenary Meeting of the United Nations General Assembly on Dec. 7. This resolution, titled “Reducing Space Threats Through Norms, Rules and Principles of Responsible Behaviours,” was originally proposed by the United Kingdom in August and seeks to identify existing and potential threats, as well as irresponsible or potentially threatening activities, for international security with an eye toward developing and implementing “norms, rules and principles of responsible behaviours and on the reduction of the risks of misunderstanding and miscalculations with respect to outer space.”

The contradiction between the international community’s diplomatic efforts to temper tensions in outer space and prevent the acceleration of the space arms race, on the one hand, and the continuous tests of counterspace technology that contribute to the escalation of such friction, on the other, is evidence that reaching true consensus on behavioral rules in outer space is no easy task.

Does Law Allow the Use of Weapons in Outer Space?

One of the best-known expressions regarding the use of outer space is that it shall be used for “peaceful purposes.” This term, often used in diplomatic discourse, interestingly appears only twice in space law’s Magna Carta—the 1967 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, also known as the Outer Space Treaty. That document states in its preamble that there is a “common interest of all mankind in the progress of the exploration and use of outer space for peaceful purposes,” and Article IV of the treaty establishes that “[t]he Moon and other celestial bodies shall be used by all State Parties to the Treaty exclusively for peaceful purposes.” The Outer Space Treaty does not define“peaceful purposes”; thus, the international community has interpreted it to mean “nonaggressive” or “nonhostile” rather than “nonmilitary.”

Although several states initially disagreed with this interpretation, most ended up aligning with the United States’s assertion—highlighted in its 2020 National Space Policy—that the principle of the use of space for peaceful purposes is consistent with national security activities in space, including the exercise of the inherent right of self-defense. As a result of this interpretation, outer space is nowadays crawling with satellites used for military purposes such as intelligence gathering, reconnaissance, navigation, targeting over battlefields, early warning of missile and air attacks, or military communications, usually without protest from the international community.

Generally, the more technologically advanced a state is, the more of these space assets it has and, therefore, the greater its interest in ensuring their safety. To that extent, the more a state relies on space technology, the more significant its vulnerability, as space assets are easily targetable and difficult to defend due to the predictability of their movements. In the face of this, states have sought to protect their interests in space through the development and testing of counterspace technology—weapons designed to impair or destroy space assets. Russia’s direct-ascent ASAT test in December is an example of this, and while the international community may express its dismay and condemn such actions, as the United States did, the existing space law regime does not expressly denounce them as illegal—a fact that spacefaring states (including the United States) take advantage of.

The Outer Space Treaty and the rest of the applicable space law establish few limitations on activities in outer space, leaving states essentially free to develop any defensive and offensive military capabilities they deem necessary to protect their national security interests in space, as long as such capabilities do not contravene international law, including the U.N. Charter, as stipulated in Article III of the Outer Space Treaty. Under Article IV of the treaty, only the placement “in orbit around the Earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner” and “[t]he establishment of military bases, installations and fortifications, the testing of any type of weapons and the conduct of military manoeuvres on celestial bodies” are prohibited. Beyond these regulations, the Outer Space Treaty does not say anything about the use of conventional weapons in the void of space; thus, states have interpreted that to be fair game as long as such weapons are not used aggressively against another space actor. ASAT testing is a result of this legal interpretation, which has garnered significant criticism over the years. Still, states have generally shied away from condemning such actions as illegal, most likely because they wish to retain the possibility of legally using ASAT technology themselves.

The use of weapons in space—as long as it is done within the bounds of the regulations described above—is legal. Nevertheless, the international community is aware of the dangers it poses. Even if an ASAT test is not directed against another nation’s technology, it serves as evidence that a state possesses the capabilities required for conducting attacks against others, should it wish to do so. Instead of serving as a deterrent, this ability to target or compromise another country’s space technology has raised tensions between adversaries. As Cassandra Steer, mission specialist with the Australian National University Institute for Space, points out, these capabilities, as well as the fear of possible reciprocation by adversaries, “have led to changes in domestic space policies and strategies by all key states and to an escalatory cycle of developing counterspace technologies, or a range of ways in which to target or interfere with each other’s space-based assets.”

The most noteworthy type of ASAT testing, which is also the one that has generated the most controversy in the international community, is the use of direct-ascent missiles (weapons designed to strike a satellite using a trajectory that intersects its target without placing the interceptor in orbit) such as the one Russia employed in its December demonstration. Four countries—the U.S., Russia, China and India—have conducted successful tests of this kind, although only the United States, China and India directed their missiles against actual objects—in all cases, satellites that belonged to the state conducting the test.

Russia, by contrast, has never conducted a kinetic kill ASAT test (involving the collision of the ASAT with its target satellite, which destroys both the ASAT and the satellite with the energy of the crash) against another space object, but it has carried out multiple successful test flights of the Nudol anti-ballistic missile—as the Dec. 15 test was presumed to be—which can be used as a defensive interceptor weapon but also has the ability to take down satellites in low Earth orbit, situated at an altitude of 160 to 2,000 kilometers (100 to 1,200 miles) above sea level.

All of these tests have provoked protests of varying degrees from the international community, but the most significant by far is the demonstration conducted by China in 2007, which was directed at, and successfully collided with, the nonoperational Chinese weather satellite Fengyun-1C at an altitude of 863 kilometers (534 miles). This test is notorious because it created huge amounts of space debris; a cloud of more than 3,000 pieces of space debris was tracked, the largest ever.

The United States criticized that test as “inconsistent with the spirit of cooperation that both countries aspire to in the civil space area.” The European Union’s condemnation was even stronger, expressing that “such a test is inconsistent with international efforts to avert an arms race in outer space.” In the face of China’s actions, the EU “call[ed] upon all signatory states [of the Outer Space Treaty] to abide by their commitment to exercise their space activities in accordance with international law and in the interest of maintaining international peace and security.” Japan’s condemnation of the ASAT test was perhaps the harshest of all since it expressly asserted that such activity constituted a violation of existing international law. Prime Minister Shinzo Abe claimed that China’s kinetic ASAT demonstration constituted a violation of the Outer Space Treaty. He did not elaborate on what clause China had violated with its actions, but some observers have speculated that Abe believed China’s test, which littered outer space with dangerous debris, to be a violation of the duty of due regard codified in Article IX of the Outer Space Treaty. Under this principle, states are bound to refrain from any acts that might adversely affect the peaceful use and exploration of outer space by other stakeholders.

These criticisms, however, were insufficient to deter other states from carrying out their own tests, even those that used kinetic weapons. When testing ASAT weapons, countries have been quick to assure the international community that they remained committed to the peaceful uses of outer space. By shielding themselves behind that language, states have continued to pursue the development of ASAT technology and have actively tested it. China’s direct-ascent ASAT test in 2007 was followed by a similar one in 2019 conducted by India (dubbed “Mission Shakti,” which means “strength” in Sanskrit) to destroy one of its own satellites, the Microsat-R satellite, in an orbit less than 300 kilometers (186 miles) high. And a year later, in 2020, Russia conducted two direct-ascent ASAT tests—one in April and one in December.

But direct-ascent tests are not the only ones countries are carrying out. Counterspace-focused activities are also being tested and performed in orbit. For example, on July 15, 2020, the U.S. Space Command reported that Russia had “conducted a non-destructive test of a space-based anti-satellite weapon” by “inject[ing] a new object into orbit from Cosmos 2543.” As Daniel Porras, director of strategic partnerships and communications at Secure World Foundation and nonresident fellow at the U.N. Institute for Disarmament Research, put it, “In essence, a Russian satellite shot a projectile into space,” much like a “space torpedo” of sorts.

Additionally, there are many other space weapons that raise concerns beyond kinetic energy ASATs. As Secure World Foundation’s Brian Weeden, director of program planning, and Victoria Samson, Washington office director, highlight, Russia has been investing heavily in modernizing its electronic warfare capabilities, China has likely been developing and testing directed energy weapons for counterspace use, Iran has demonstrated an electronic warfare capability to persistently interfere with commercial satellite signals, and North Korea has been working toward growing its capabilities in two counterspace weapons categories: electronic and cyber.

And while all of these activities might sound undesirably dangerous, and contradictory to the principles of peace and cooperation enshrined in the Outer Space Treaty, they are considered to be within the bounds of legality established by all applicable regulations, including the Outer Space Treaty. Nevertheless, the international community has recognized the worrisome nature of these behaviors in space and has attempted to regulate them more clearly under the banner of the Prevention of an Arms Race in Outer Space (PAROS), an expression used to acknowledge that the Outer Space Treaty by itself does not guarantee the prevention of an arms race in outer space and to advocate for the implementation of further measures to prevent an arms race in outer space.

Efforts to Avoid the Weaponization of Space: The Prevention of an Arms Race in Outer Space (PAROS)

ASATs, and states’ interest in developing them, are not new. After the successful launch of Sputnik in 1957, both the U.S. and the U.S.S.R. spearheaded the pursuit of diverse ASAT weapons systems in an effort to protect their military and national security interests in space. The international community feared that, if left unchecked, the Cold War rivalry that existed between the two countries could extend to outer space. This concern prompted the creation of the Committee on the Peaceful Uses of Outer Space (COPUOS), and it was under the committee’s auspices that the Outer Space Treaty was drafted, with a key objective of serving as an arms control treaty. The treaty, however, as well as the subsequent treaties adopted by the U.N. that regulate space, left a lot of wiggle room for states to legally use conventional weapons in space. To address this issue, which many states perceive as a regulatory deficiency of the space treaties, the Conference on Disarmament established an ad hoc committee in 1985 to examine issues related to PAROS, including proposals and initiatives for regulating it.

The committee was largely unsuccessful in its mission to contribute to achieving PAROS, largely due to the United States’s refusal to give it a negotiating mandate. Ultimately, the committee ceased to be convened after 1994 due to the U.S.’s persistent objections. The United States believed bilateral negotiations with what then was the only other space power, the Soviet Union, would yield more results—a position likely motivated by the lack of success of the 1984 Moon Agreement, formally termed the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, which currently has only 18 state parties and has been signed, but not ratified, by an additional four states. However, it is possible that the U.S.’s opposition to the PAROS committee was also due to its interest in maintaining the freedom of action that the broad and permissive language of the Outer Space Treaty allowed.

Despite the lack of success of the ad hoc committee, the idea of PAROS managed to survive, and a majority of U.N. member states now acknowledge the need for some sort of multilateral regulation that addresses the matter of space weaponization. To that extent, upon the recommendation of the Committee on Disarmament and International Security (First Committee), the U.N. General Assembly passes several resolutions relating to security in outer space every year. During the 75th session of the U.N. General Assembly, four resolutions that tackle this issue were adopted. Three of the resolutions—“Transparency and Confidence-Building Measures in Outer Space Activities,” “No First Placement of Weapons in Outer Space,” and “Prevention of an Arms Race in Outer Space”—reiterate resolutions adopted in previous sessions. The fourth—“Reducing Space Threats Through Norms, Rules and Principles of Responsible Behaviours”—is the U.K.’s new proposal, which seeks to encourage member states to “share their ideas on the further development and implementation of norms, rules and principles of responsible behaviours and on the reduction of the risks of misunderstanding and miscalculations with respect to outer space.” The U.K. proposal is different from previous attempts to regulate behavior in outer space, according to Rajeswari Pillai Rajagopalan, distinguished fellow and head of the Nuclear and Space Policy Initiative at the Observer Research Foundation, because it “focus[es] on a behaviour-based approach” as opposed to object-based approaches which have not been very successful. As Rajagopalan points out, “The U.K. proposal is not prescriptive in suggesting a particular type of outcome or a particular format. Thus, this proposal provides room for greater flexibility and certain amount of manoeuvring among member states as they debate the threats and challenges and possible ways forward.”

Among the previous attempts to address the issue of arms control in space that failed—in part due to their object-based approach—one of the most noteworthy is the European Union’s Draft International Code of Conduct for Outer Space Activities. The first drafts of this attempt at establishing nonbinding norms of responsible behavior in space activities were authored and agreed upon within the internal structures of the EU, and it was released for the first time to the international community in December 2008. Despite undergoing several revisions—which led to new versions in 2010, 2012, 2013 and 2014—the code failed to garner enough support from the international community, receiving mixed reviews. Several states, particularly emerging space powers, objected to the way the code was negotiated within the EU, without involving others in the process from the outset. There were also substantive concerns due to its vague terminology and lack of definitions, with some states (such as the U.S.) expressing that it was too restrictive and others that it was not restrictive enough. Although several countries, including the U.S., Australia and Japan, announced that they would be willing to initiate a multilateral negotiating process to develop an International Code of Conduct, using the EU draft as a foundation, the United States eventually withdrew its support from the project in 2015, driving one last nail into the code’s coffin.

However, the most significant attempt at creating an arms control agreement for outer space is the Sino-Russian 2008 Draft Treaty on the Prevention of Placement of Weapons in Outer Space and the Threat or Use of Force Against Space Objects (dubbed PPWT). This proposal of a legally binding multilateral agreement on the issue of preventing an arms race in space, submitted to the Conference on Disarmament, failed to generate adequate support, both in 2008 and when a new version was submitted in January 2014. The main critic of the PPWT is the U.S., since it believes the PPWT to be “fundamentally flawed”—a sentiment shared by many other states. Some of the more criticized aspects of the PPWT include the lack of a verification mechanism; the lack of restrictions on the development and stockpiling of ASAT weapons on the ground; and the fact that while the PPWT bans the placement of weapons in outer space, it does not ban direct-ascent ASATs launched from the ground, such as the one used by Russia in its December test, nor does it address soft-kill weapons such as lasers that could be employed to permanently or temporarily disable a satellite.

Is There a Way Forward to Prevent the Weaponization of Outer Space?

The diplomatic efforts to prevent the weaponization of outer space seem to indicate that the international community is concerned about the dangerous consequences that an arms race in outer space entails. But outside of the diplomatic arena, the actions of spacefaring states tell a different story. Russia is a prime example: Despite being one of the main proponents of a binding agreement that aims to ban weapons in space, Russia carried out three separate tests of counterspace weaponry in 2020 alone—two direct-ascent ASAT demonstrations, on April 15 and Dec. 15, and one co-orbital ASAT test on July 15. These actions have further fueled the mistrust in Russia’s behavior and intentions in outer space—a sentiment that has been expressed repeatedly by the United States and its allies.

As Daniel Porras suggests, these tests are evidence that Russia is “hedging its bets by ensuring that if it becomes necessary to strike a space object, they will be in a position to do so.” In the face of the United States’s outright refusal to bind itself to a treaty it considers to be deeply flawed, Russia, China and others continue to develop their counterspace capabilities, leaving the international community at an impasse: While states acknowledge the importance of PAROS, no one wants to be the first to commit to ASAT disarmament. As long as this is the international community’s mindset, counterspace weaponry demonstrations will continue. The problem is that a test carried out by one country inspires others to follow suit, thus contributing to dangerous escalations, which are slowly but surely turning PAROS into a misnomer because an arms race in outer space is becoming less of an issue to prevent but, rather, one that has to be stopped.

It is therefore crucial that the international community cease viewing PAROS as a binary issue—treaty or no treaty. As Samson commented, “Space security and stability will not be achieved via one path—it will take a variety of approaches to make it a secure, predictable environment for all.” To that end, the U.K. proposal, with its behavior-based approach that allows U.N. member states to identify threats and challenges from their own national security perspectives, presents itself as a more flexible option that might achieve what previous attempts have failed to do: bring the different space powers—both established and emerging—to the negotiating table for a fruitful discussion that eventually results in actionable measures that deescalate tensions and prevent an arms race in outer space. Russia’s and China’s votes against the resolution, as well as India’s abstention, however, indicate that the U.K.’s proposal is not the ultimate solution to the weaponization of outer space. It is nevertheless a welcome step that will hopefully lead the international community to progress on the issue of PAROS.

Almudena Azcárate Ortega is a space security researcher at the United Nations Institute for Disarmament Research (UNIDIR). She has published widely and briefed UN member states on the topics of space security law and policy and has presented her research in multiple fora. She is currently a doctoral candidate at Georgetown Law and holds an LL.M. in national security law from the same institution. She received her bachelor’s degree from the University of Navarra, Spain.

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