International Order & Conflict
Research Pages

Key Elements of Space Assurance

in Program


The first use of space weapons during war would be an historic act, and could have catalytic effects in space, as well as on the ground. All states that derive benefits from satellites could be punished by space warfare. However, none more so than the United States, which employs satellites for commercial, military, communications, early warning, scientific and intelligence functions. To safegaurd our forces and assets we should adopt a space assurance posture. Follow the links below to review the key elements of a space assurance regime.




Maintaining US Conventional Military Superiority


Increasing Situational Awareness of Space Activities

Strengthening International Norms to Prevent Incidents and Dangerous Military Practices in Space


Supporting a Code of Conduct for Responsible Space-Faring Nations

Adopting a Hedging Strategy to Deter Others from Flight Testing and Deploying Space Weapons


Abstaining from Flight Testing and Deploying Space Weapon


Read Michael Krepon’s tesimony to the House Armed Services Committee on

“Promoting US National and Economic Security Interests in Space” here.


Read more about Space Assurance in the Stimson Center Monograph:

Space Assurance or Space Dominance? The Case Against Weaponizing Space



Key Element: Maintaining US Conventional Military Superiority

The United States enjoys unparalleled and unprecedented military superiority. The US will spend close to half a trillion dollars this year on defense (over three times more than Russia, its closest peer competitor). In the 2003 Iraqi war, 130,000 troops decimated opposing forces and occupied a country the size of Montana in three weeks.

US conventional superiority provides a powerful deterrent and response to any other state that seeks to damage US space assets-particularly when asymmetric attacks against US space assets are far easier to assign responsibility to than asymmetric warfare waged against soft targets here on earth.

Key Element: Strengthening International Norms to Prevent Incidents and Dangerous Military Practices in Space

Space law is a relatively new, dynamic field evolving from widely recognized international norms of responsible behavior in space. Although strengthening international norms does not protect against aggressive activity in space, it does clarify misbehavior, therefore facilitating efforts by responsible space-faring nations to respond harshly to irresponsible act in space.

Legal Norms

  1. 1967 Outer Space Treaty
    • Recognizing the common interest of all mankind in the progress of the exploration and use of outer space for peaceful purposes,
    • Believing that the exploration and use of outer space should be carried on for the benefit of all peoples irrespective of the degree of their economic or scientific development,
    • Desiring to contribute to broad international cooperation in the scientific as well as the legal aspects of the exploration and use of outer space for peaceful purposes,
    • Believing that such cooperation will contribute to the development of mutual understanding and to the strengthening of friendly relations between States and peoples,
    • The exploration and use of outer space, including the Moon and other celestial bodies, shall be carried out for the benefit and in the interests of all countries, irrespective of their degree of economic or scientific development, and shall be the province of all mankind.
    • Outer space, including the Moon and other celestial bodies, shall be free for exploration and use by all States without discrimination of any kind, on a basis of equality and in accordance with international law, and there shall be free access to all areas of celestial bodies.
    • There shall be freedom of scientific investigation in outer space, including the Moon and other celestial bodies, and States shall facilitate and encourage international cooperation in such investigation.
    • Outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.
    • States Parties to the Treaty shall carry on activities in the exploration and use of outer space, including the Moon and other celestial bodies, in accordance with international law, including the Charter of the United Nations, in the interest of maintaining international peace and security and promoting international cooperation and understanding.
  2. 1968 Astronaut Rescue Agreement
    • Noting the great importance of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, which calls for the rendering of all possible assistance to astronauts in the event of accident, distress or emergency landing, the prompt and safe return of astronauts, and the return of objects launched into outer space,
    • Desiring to develop and give further concrete expression to these duties,
    • Wishing to promote international cooperation in the peaceful exploration and use of outer space,
    • Prompted by sentiments of humanity.
  3. 1972 Liability Convention
    • Recognizing the common interest of all mankind in furthering the exploration and use of outer space for peaceful purposes,
    • Recognizing the need to elaborate effective international rules and procedures concerning liability for damage caused by space objects and to ensure, in particular, the prompt payment under the terms of this Convention of a full and equitable measure of compensation to victims of such damage,
    • Believing that the establishment of such rules and procedures will contribute to the strengthening of international cooperation in the field of the exploration and use of outer space for peaceful purposes.
  4. 1975 Registration Convention
    • Recognizing the common interest of all mankind in furthering the exploration and use of outer space for peaceful purposes.
  5. 1979 Moon Agreement
    • Determined to promote on the basis of equality the further development of cooperation among States in the exploration and use of the Moon and other celestial bodies,
    • Desiring to prevent the Moon from becoming an area of international conflict,
    • Recalling the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, the Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space, the Convention on International Liability for Damage Caused by Space Objects, and the Convention on Registration of Objects Launched into Outer Space.

Customary Norms
  1. No Flight-Testing of ASATs
  2. No Deployment of Space Weapons
  3. No Aggressive Actions in Space

Key Element: Adopting a Hedging Strategy to Deter Others from Flight Testing and Deploying Space Weapons

Destroying ground-based control facilities associated with satellite operations may be a more feasible option for future US adversaries than initiating space warfare, particularly when large constellations of target satellites are supported by a small number of terrestrial facilities, as is the case with the GPS system. In such circumstances, the loss of a few ground stations would have negative consequences for GPS performance across the globe. The same argument applies to attacks on the ground segment of observation satellites, early warning satellites, and weather satellites. Clearly, there is benefit in diversifying and multiplying ground segment nodes, as is the case for some communication satellites in GEO. Cyber attacks against critical infrastructure, including satellite operations, must receive priority attention, as this threat appears more likely than the threat of physical destruction of satellites in space. The Homeland Security Act’s inclusion of satellites within the classification of critical infrastructure should accelerate risk reduction measures in this regard.

< Building Block: Maintaining Laboratory Research and Development and Indoor Testing of Retaliatory Space Warfare Capabilities >

The United States will continue to rely upon deterrence and devastating military responses to protect its space assets. The United States maintains many military capabilities designed for other purposes that could be employed against an adversary’s satellites in an emergency. These latent or residual capabilities reinforce deterrence and constitute yet another form of insurance against space warfare. In this context, deterrence does not require dedicated ASATs or flight tests and deployments of space weapons, since it is well understood that weapon systems designed for other purposes have the inherent capability to disrupt or destroy satellites. Indeed, these residual capabilities are growing, as the United States pursues advanced missile defenses and the airborne laser program that are designed for other missions but that could, if needed, be utilized against the satellites of a state that initiates space warfare. There are, in sum, numerous and growing ways for the United States to convey messages abroad that those who engage in space warfare against U.S. assets can expect to fail in their intended purpose and to reap significant penalties. The United States does not need to flight-test and deploy space weapons, whether offensive or “defensive” in nature, to underscore these messages.

< Building Block: Adopting Defensive Measures >

Satellite Maneuverability

Adding satellite maneuverability might well be more useful than hardening or armoring. While a 10-ton imaging satellite would have a hard time escaping from a highly maneuverable homing ASAT, some potential adversaries fielding much cruder ASATs might have difficulty dealing with maneuverable targets. The costs of adding thrusters and strengthening the satellite for higher structural loads are estimated to be between ten and twenty percent of total system costs. For certain high-value satellites, and particularly those in higher orbits that have more time for evasive maneuvers, this additional cost might be deemed worthwhile.

Satellite Hardening

Against Jamming

Space systems face jamming threats both to the communications link from the ground to the satellite and from the satellite back to the ground, or to the uplink and the downlink, respectively. In general, uplink jamming is more difficult because the jammer must be roughly as powerful as the ground-based emitter in order to overwhelm the signal received at the satellite’s antenna. Jamming can be complicated by techniques such as spread-spectrum transmission. Downlink jammers, on the other hand, can frequently be much less powerful and still be effective because they are much closer to the receiver than the source of the signal (the satellite). Many U.S. receivers, such as GPS systems on precision munitions, use special directional receiving antennas that mitigate all but the most intense jamming. The U.S. military will shy away from solely jam-resistant communication satellites because of the high costs involved. However, it is possible to envision an improved communication architecture that mixes jam-resistant systems with fiber optic capacity and more vulnerable commercial and military satellite transmissions bandwidth. Beyond communications, the U.S. military has already included antijamming features in its upgrades to the GPS satellite constellation. The Defense Advanced Research Projects Agency continues to work with pseudo-satellites (“pseudolites”) on the land and in the air to boost the GPS signal and “burn” through the jamming. “Filters” can be added to non-space components to allow them to better sort through the jamming noise and pick up the true signal.

Against Electromagnetic Pulse
Satellites can be hardened by factors of about ten against externally generated electronic pulses created by nuclear detonations. Satellite construction costs may grow by up to perhaps ten percent as a result, but for military satellites in particular, the added costs are hardly onerous. It is more difficult to harden equipment against system-generated electromagnetic pulse phenomena, which is likely to be a dubious financial proposition for commercial satellites. Hardening against electromagnetic pulse for satellites in MEO and GEO might be less of an imperative, since distances between satellites are greater at those altitudes. On-orbit spares or replacements on the ground can substitute for those satellites rendered inoperable.

Against Radiation
Satellites can be hardened somewhat against electrons and other radiation generated by nuclear explosions. This is an imperative for satellites in LEO, since radiation generated from nuclear bursts can be trapped in these orbits, destroying all non-hardened satellites over a period of weeks or months. The resulting radiation would slowly dissipate, requiring perhaps 18 months of waiting before non-hardened replacements would experience near-normal lifespans. Hardening against radiation would add perhaps two to five percent to total system cost. It seems unlikely that the space industry would harden its satellites without significant prompting and subsidization from government entities. An additional effect from radiation in space is “transient radiation effects on electronics,” or TREE. Ionizing radiation, particularly high-energy electrons, passing through electronic equipment can cause currents to flow where they should not, short-circuiting or burning out microcircuitry. TREE can also cause highly integrated chips to fail because the charge state of the microscopic transistors in those chips is changed by the passage of a charged particle. The smaller the chip, the more transistors packed into it, the greater is the probability of such an “upset” failure. While the upset might heal, it is possible that the equipment will be out of commission for some period. If the upset is so great as to require a reboot of the software, the time lost could become extremely significant.

Replacement Satellite Readiness

It is impossible to harden satellites against direct assaults by kinetic energy ASATs. The closing velocities and masses involved are simply too great for metals to withstand. Normal closing velocities in space are likely to be between 10 and 20 km/second. Hardening against explosives or ramming is therefore likely to be expensive as well as futile. Additionally, hardening would seriously reduce the life span of the satellite and significantly raise production and launch costs without providing suitable protection. Therefore it is advisable to have back-ups, spares, or alternative means ready to replace or compensate for satellite losses. If potential adversaries know or presume that multiple attacks against satellites would be required to impair American military capabilities on the ground, and that US space assets could be quickly reconstituted, they might well conclude that the initiation of space warfare would be both inadvisable and unsuccessful. However, as noted above, these measures would not be successful if an adversary detonates a nuclear weapon of sufficient yield anywhere above 100 km altitude.

Satellite Redundancy

Since satellite protection cannot be guaranteed, redundancy could provide partial, but useful, insurance against potential threats. A prompt ability to reconstitute or compensate for systems that have been attacked could also foil attacking plans. Insurance policies to reduce the risks associated with satellite vulnerability remain vital investments in national security. No single satellite must become so essential that its loss would result in catastrophe.

Back-Up Systems

The possibility of “single point failures”-the loss of a single component or a single satellite that would result in significant or long-lasting losses of critically important data-must be dramatically reduced. Even if back-ups prove less capable or efficient than the satellites lost, they would address the risks attendant to single-point failures resulting in significant degradation of U.S. military capabilities. Of particular note in this regard are advances in unmanned aerial vehicles. Looking toward the future, airborne assets, particularly for imaging and signals intelligence, but also for targeting, guidance, and communications, could be available to supplement, or, if need be, help compensate for satellites that are destroyed. Significant advances in remotely piloted vehicles could reinforce the conclusion by potential adversaries that the initiation of space warfare would produce ephemeral gains and punishing retaliation. Additional backup capabilities such as fiber optic land lines and undersea lines could prove helpful in some regions of the world to permit high-volume communications even if satellites are lost. Fiber optic capability could be leased at pre-set prices for use during crisis, analogous to the way that the Civil Reserve Air Fleet functions today. US naval combatants can be expected to retain the ability to communicate through line-of-sight and airborne techniques, so that battle groups have the ability to function as integrated entities even if their access to satellites is disrupted. Netted tactical data link systems provide relative navigation among net members. While not as accurate as GPS, netted systems, such as the Joint Tactical Information and Distribution System, mitigate the harm caused by jamming or more pernicious damage to the GPS system.

Key Element: Improving Situational Awareness in Space

Space Assurance requires improved situational awareness of developments in space, particularly those of a potentially threatening nature. Improved situational awareness could provide early and repeated warnings of unwelcome developments warranting a US response. Increased situational awareness could clarify to potentially hostile states that unwelcome steps will be detected promptly, thereby increasing the prospect of deterrence, at least in some cases. In addition, increased transparency of space activities and an improved US ability to characterize developments in space could help convince some potential adversaries that they cannot carry out stealthy attacks on U.S. satellites with the expectation of plausible deniability. Better tracking of space debris can be used for collision avoidance. Improved monitoring techniques could also lay the groundwork for cooperative measures for space-related activities. Lastly, steps to improve situational awareness in space could increase the possibility that future US decisions regarding space warfare initiatives could be made more on the basis of informed judgment than on surmise.

Situational awareness can be improved through unilateral measures and through cooperative arrangements with other nations or consortiums that have space launch capabilities. Cooperative threat reduction measures relating to space are discussed elsewhere. Unilateral steps to increase US awareness of the space operations of others, including nations that might at some future date decide to engage in space warfare, are discussed below.

There are a number of ways in which the United States could improve situational awareness in space. Improved capabilities in X-band radars currently being developed for missile tracking as part of a national missile defense system could also be tasked for space and debris monitoring. Additional X-band systems could be brought online to supplement the current, less accurate, C-band systems. The optical cameras that track objects in space, known as the Ground-Based Electro-Optical Deep Space Surveillance System, have undergone upgrades in recent years that, when complete, will allow the system to do an adequate job at monitoring those orbits. Information collected by these sensors has to be processed, filtered, organized, and stored. These data points are then used to build models of orbits using complicated algorithms. The algorithms being used, created when computer processors were significantly slower than today, could be updated to create a more accurate picture of the environment. Automation and filtering software needs to be used to “mine” the data and minimize the time required of human operators, a significant potential bottleneck in the cataloguing process. Space-based sensors would also provide expanded understanding of the threat environment. There has been some discussion of using the Space-Based Infrared Sensors-High for space threat detection.

Additionally, few, if any, current satellites appear to carry the kind of long- and short-range detection systems needed to tell if the satellite is under attack, or even being closely approached by another object. Adding an on-board system for attack reporting would likely increase total system cost by between one and five percent and would probably require some kind of low-power 360-degree radar or proximity fuse system to detect the approach of another object.

Key Element: Supporting a Code of Conduct for Responsible Space-Faring Nations

A code of conduct for responsible space-faring nations could strengthen international norms against dangerous military activities in space. A code of conduct could take the form of bilateral or multilateral executive agreements. During the Cold War, the United States entered into executive agreements with the Soviet Union to prevent dangerous military practices at sea, on the ground, and in the air. For example The US-Soviet Incidents at Sea (or INCSEA) accord has served as a model for comparable agreements signed by more than thirty other navies. A similar approach could also provide reinforce space assurance, while facilitating collective efforts to counter states that engage in dangerous military practices in space.



In order to extend its deterrence concepts and defense capabilities to space, the US will require…engaging US allies and friends, and the international community, in a sustained effort to fashion appropriate “rules of the road” for space.

                                                  – Rumsfeld Space Commission Report


The pursuit of a code of conduct or rules of the road for responsible space-faring nations might draw and expand prior terrestrial precedents. This effort would need to surmount many challenges, including how to define what constitutes dangerous military practices in space and how to devise suitable transparency measures to provide assurance of compliance or to warn of possible noncompliance. While executive agreements have the same standing as treaties in international law, this approach, even if widely replicated, is unlikely to be as inclusive as a multilateral treaty negotiated at the Conference on Disarmament. As with efforts to negotiate an international convention, important space-faring nations might not choose to join. The choice between a code of conduct and an international convention is not mutually exclusive. To the contrary, executive agreements establishing a code of conduct to prevent dangerous military practices in space could facilitate the eventual negotiation of a multilateral treaty that is more ambitious in scope.

Abstaining from Flight Testing and Deploying Space Weapons

The flight testing and deployment of space weapons by the United States would surely prompt low-cost, low-tech countermeasures in the form of space mines and other anti-satellite (ASAT) devices, just as the flight testing and deployment of space weapons by other countries would surely prompt a vigorous response by the United States.  A situation in which satellites orbiting the earth are interspersed with objects designed to destroy or disable them is inherently destabilizing, given the vulnerability of satellites and the ease with which they could be harmed.  Potential adversaries in space would be faced with the dilemma of shooting first or risking the loss of critical satellites. 

While asymmetric warfare can be carried out in space, it is more easily and effectively waged on the ground. And unlike the superpower competition in the Cold War, when space warfare had the potential to alter the terms and outcomes of conflict, space warfare initiated by a weaker foe will not alter the outcome of a conflict with the United States.

A Space “Pearl Harbor” cannot be automatically dismissed. But a military readiness response in the form of space weapons would do far more harm than good. A surprise attack in space is far less likely than a surprise attack against soft targets here on earth and would subsequently generate a response no less resolute than previous surprise attacks in December 1941 and September 2001. Furthermore, such a response would be carried out most effectively here on earth, and not in the Heavens. Nonetheless, to further clarify the penalties to others for the first use of space weapons, the United States would be wise to adopt a hedging strategy that includes research and development – but not the flight testing and deployment – of space weapons.

Other nations are similarly also engaged in research and development programs relating to space warfare.  There is no compelling need, however, to engage in the flight testing and deployment of dedicated space weapons, in part because the United States and many other nations already possess military capabilities designed for other missions that could, in extreme circumstances, serve as a response to the first use of space weapons by another state.  Such “residual” space warfare capabilities have paradoxically served as a brake against the flight testing and deployment of space weapons in the past.  

The weaponization of space is not inevitable.  If it were, this would have occurred during the Cold War.  Rather than to engage in such a competition now, a far wiser course would be to strengthen efforts to promote space assurance.


Photo Credit: Flickr, Nasa Goddard Photo and Video,

Share on twitter
Share on facebook
Share on linkedin
Share on email
Choose Your Subscription Topics
* indicates required
I'm interested in...
38 North: News and Analysis on North Korea
South Asian Voices