APRIL 3, 2019

Satellite Jamming
A Technology Primer
BY PAVEL VELKOVSKY, JANANI MOHAN, AND MAXWELL SIMON

TYPE CHARACTERISTICS RISK FACTORS

Electronic Warfare Precision, Persistance, Resiliency, Action-enabling, First-mover incentive
Speed

DOMAIN COUNTRY
Space, Land, Air, Sea United States, Russia, China,
Non-state actors

“The global threat of electronic warfare attacks against space systems will
expand in the coming years in both number and types of weapons.
Development will very likely focus on jamming capabilities.”1
– U.S. Director of National Intelligence Dan Coats, May 2017

Introduction
Satellite jamming is a form of electronic anti-satellite (ASAT) attack that interferes with communications traveling
to and from a satellite by emitting noise of the same radio frequency (RF) within the field of view of the satellite’s
antennas.2 Considered a growing threat by the U.S. intelligence community, jamming equipment operates
across multiple domains.

All space capabilities are made up of a ground segment and a space segment, as well as the communication, or
link, that ties them together. Satellite jammers threaten adversary capabilities via the communication segment
and can be used from the ground, ocean surface, or air. In contrast to kinetic physical counterspace weapons,
such as direct-ascent ASAT missiles, or non-kinetic physical weapons, such as lasers or high-powered
microwaves (HPM), jamming does not physically damage satellites. It is an entirely reversible form of attack
because once the jamming signal is turned off, adversary communications are restored.3

1U.S. Congress, Senate, Senate Select Committee on Intelligence, Worldwide Threat Assessment of the U.S. Intelligence
Community, 115th Cong., 1st sess., (2017), 32.
2Brian Garino and Jane Gibson, “Space System Threats,” AU-18 Space Primer (Maxwell Air Force Base: Air University
Press, 2009), p. 274; Todd Harrison, Future of MILSATCOM (Washington, DC: Center for Strategic and Budgetary
Assessments, 2013), p. 10; Todd Harrison, Kaitlyn Johnson, and Thomas G. Roberts, Space Threat Assessment 2019
(Washington, DC: CSIS, April 2019), 4.
3 Ibid., 4.

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There are two main types of satellite jamming. The first, uplink jamming, interferes with the signal going from a
ground station or user terminal to the satellite. An RF signal of the same frequency as the targeted uplink signal
is transmitted to the satellite, aiming to limit the satellite transponder from differentiating between the jamming
signal and the actual signal.4 The second type, downlink jamming, disrupts transmissions sent from the satellite
to ground-based or airborne receivers using RF signals that mimic the frequency of the downlink signal. It aims
to inhibit ground users from receiving transmissions from the satellite and only needs to be as strong as the
signal being received on the ground. 5 Uplink jamming is considered more difficult because greater transmitter
power is required to reach a given satellite’s transponders. It could be more impactful, however, due to its ability
to degrade the satellite’s signal for all its users.6 Because downlink jammers must be within the field of view of
the receiving terminal’s antenna, however, the effects of downlink jamming are more localized.

Jamming technology tends to be commercially available and relatively inexpensive. Satellite jamming systems
are easy for states and non-state actors to develop given the relative low cost of their procurement and
operation. There is a low threshold of technological competency required to perform jamming, and the
technology is available to a plethora of actors across the globe. For example, interference with satellite signals
has emanated from Indonesia, Cuba, Ethiopia, Libya, and Syria, among others. 7 Furthermore, simple terrestrial
jamming systems are cheap and commercially available, despite being illegal under both U.S. FCC laws and
rules of the International Telecommunications Union.8 Recent improvements in such commercial jammers
include reductions in size from jammers about the size of a Frisbee to those the size of a hockey puck. 9 As a
consequence, there are few downsides to developing jamming capabilities.

Jamming can also occur accidentally: in 2015, U.S. military officials noted they were unintentionally jamming
satellite communications an average of 23 times per month.10 Purposeful jamming can be difficult to
differentiate from accidental interference, making attribution more challenging. According to General John
Hyten, then-commander of the Air Force Space Command, U.S. military personnel lack “awareness of what our
own forces are doing in the spectrum, let alone of what an adversary might do.”11

State of Play
Technology for satellite jamming has been in use for several decades. During World War II, states disrupted
adversary radio broadcasts with the same principles used in satellite jamming. For example, in Germany, the

4 Garino and Gibson, “Space System Threats,” 275.

5 Harrison, Johnson, and Roberts, Space Threat Assessment 2019, 4.
6 Harrison, Future of MILSATCOM, 11.
7Ronald G. Wilgenbusch and Alan Heisig, “Command and Control Vulnerabilities to Communications Jamming,” Joint Force
Quarterly 69, no. 2 (2013): 58.
8“GPS, Wi-Fi, and Cell Phone Jammers Frequently Asked Questions,” Federal Commerce Commission Enforcement
Bureau, https://transition.fcc.gov/eb/jammerenforcement/jamfaq.pdf; David Bosco, “When Can States Jam Radio
Broadcasts?” Foreign Policy, October 5, 2012, https://foreignpolicy.com/2012/10/05/when-can-states-jam-radio-broadcasts/.
9Mike Gruss, “Companies See Market for Systems to Counter GPS Jamming Devices,” SpaceNews.com, December 5,
2014, https://spacenews.com/37706companies-see-market-for-systems-to-counter-gps-jamming-devices/.
10Sydney J. Freedberg, Jr., “US Jammed Own Satellites 261 Times; What If Enemy Did?” Breaking Defense, December 2,
2015, http://breakingdefense.com/2015/12/us-jammed-own-satellites-261-times-in-2015-what-if-enemy-tried/.
11 Ibid.

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Nazis blocked radio signals from Western media outlets.12 Since then, jamming has advanced to include
disrupting the radio signals sent to and from civilian, commercial, and military satellites. The United States has
developed its own electronic attack systems, such as the Counter Communications System (CCS). 13 The CCS
is a land-based jammer development program operated by the U.S. Air Force to temporarily jam signals from
adversaries’ satellites. Originally operationalized in 2004, the CCS has undergone several advancements, most
recently to upgrade its operating system to an updated block configuration. 14

Several other countries have also developed satellite jamming capabilities, including China and Russia. These
two countries own sophisticated satellite jamming vehicles, with stronger signals and more maneuverability than
previous systems. In Russia, “electronic warfare systems”—such as the Krasukha-2, Zhitel, and Borisglobesk-
2—have been deployed in battlefields in Syria to jam adversary communications. 15 These systems involve
vehicles carrying satellite jamming devices originally developed in the 1980s with recent upgrades to increase
maneuverability and reduce their vulnerability to heat-seeking missiles.16 Although these developments have
increased the military utility of Russian jamming, they are not a fundamental departure from previous jamming
technology.17 System vulnerabilities still remain, including that vehicles can only jam signals in one direction in a
relatively narrow band of frequencies. Meanwhile, China also has formidable satellite jamming capabilities.
Although it has focused resources on kinetic ASAT technologies, China originally bought jamming systems from
Ukraine in the 1990s and used this technology to develop its own capabilities. 18 More recently, China deployed
military-grade satellite jamming equipment on contested islands in the South China Sea, and U.S. intelligence
suggests that they will have an operational ASAT weaponry system within the next few years. 19

Militaries are becoming increasingly reliant on technology that is vulnerable to jamming due to the importance of
constant coordination and communication in modern warfare, especially via satellites. As such, in addition to
jamming capabilities, several states have developed countermeasures to reduce susceptibility to interference.
One such method is frequency hopping spread spectrum (FHSS), which makes it more difficult for a jammer to
match RF signals by using a pseudorandom sequence.20 The sequence is known to the transmitter and receiver
and is used to spread the signal across a wider frequency range, also making the signal harder for an adversary
to detect.

12 Serge Schmemann, “Soviet Union Ends Years of Jamming Radio Liberty,” New York Times, December 1, 1988,
https://www.nytimes.com/1988/12/01/world/soviet-union-ends-years-of-jamming-of-radio-liberty.html.
13 “U.S. Satellite Jamming Systems,” Spyflight, https://spyflight.co.uk/space/#Jamming.
14 “HarrisAwarded Counter Communication System Contract,” SIGNAL Magazine, November 4, 2016,
https://www.afcea.org/content/Blog-harris-awarded-counter-communication-system-contract.
15 Sergey Sukhankin, “Russian Electronic Warfare in Ukraine: Between Real and Imaginable,” Eurasia Daily Monitor, May
24, 2014.
16 RogerN. McDermott, Russia’s Electronic Warfare Capabilities to 2025: Challenging NATO in the Electromagnetic
Spectrum (Tallinn, Estonia: International Center for Defense and Security, September 2017).
17 Ibid., 14.
18Todd Harrison, Kaitlyn Johnson, and Thomas G. Roberts, Space Threat Assessment 2018 (Washington, DC: CSIS, April
2018), 10.
19 MichaelR. Gordon and Jeremy Page, “China Installed Military Jamming Equipment on Spratly Islands, U.S. Says,” Wall
Street Journal, April 9, 2018, https://www.wsj.com/articles/china-installed-military-jamming-equipment-on-spratly-islands-u-s-
says-1523266320; Sandra Erwin, “U.S. Intelligence: Russia and China Will Have ‘operational’ Anti-satellite Weapons in a
Few Years,” Space News, September 14, 2018, https://spacenews.com/u-s-intelligence-russia-and-china-will-have-
operational-anti-satellite-weapons-in-a-few-years/.
20 Harrison, Future of MILSATCOM, 25.

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Within the space segment of the information transmission process, antenna notching and nulling can be used to
improve resistance to jamming. Antenna notching blocks signals of certain frequencies from being received,
while antenna nulling blocks signals transmitted from a specific geographical location, such as the location of a
suspected uplink jammer.21

To avoid proliferating transmission errors that arise from uplink jamming back to receivers via the downlink,
systems can decode information on a satellite before retransmitting it to another user in a process called on-
board processing.22 Finally, since RF interference tends to occur in bursts rather than in a steady and
predictable stream, successful jamming leads to errors in contiguous parts of a transmission of data. As such,
interleaving describes the process whereby data is shuffled before transmission and then reconfigured after it is
received. This strategy improves resistance by lowering the likelihood that a burst of interference would create
multiple errors within a single data packet.23 As a result of the shuffling and reshuffling process, however,
interleaving slows data transmission speed. When used together, these defenses can significantly improve
resilience to jamming.

In the United States, recent research and development has focused on building protection into satellite
communications. The Trump administration’s FY 2020 budget requested $174 million to accelerate development
of a Protected Tactical Satellite Communications (PTS) system and proposed another $105 million for
development of the PTS ground system known as the Protected Tactical Enterprise Service (PTES). 24 The Air
Force plans to eventually complete a family of PTS systems, with space, ground, and gateway segments all
connected.25 It has also already developed Advanced Extremely High Frequency satellites that incorporate the
previously mentioned jamming technology to achieve “a high degree of protection.” 26

Effects on Situational Awareness

Satellite jamming capabilities are often intended to disrupt the sensor-shooter kill chain by lowering an
opponent’s level of situational awareness—their ability to characterize the operating environment and detect
attacks. Jamming can disrupt missile warning systems, impede access to GPS, and decrease precision and
persistence.27 Interference with transmissions could interrupt one’s ability to continuously collect and transmit
data, thereby decreasing the data’s reliability and accuracy.

Jamming capabilities would also, by definition, degrade an opponent’s resiliency. In a contested environment,
jamming could make it harder to effectively rely on missile warning satellites, perform reconnaissance, collect
intelligence on the battlefield, and maintain communication. Opponent forces would have lower situational
awareness as they would acquire less intelligence about the battlefield and would have more trouble
communicating among themselves.

21 Harrison, Future of MILSATCOM, 26.

22 Ibid.
23 Ibid.

24 Sandra Erwin, “Military Space Gets Big Boost in Pentagon's $750 Billion Budget Plan,” Space News, April 1, 2019,
https://spacenews.com/militaryspace-gets-big-boost-in-pentagons-750-billio/.
25 Ibid.
26 Harrison, Johnson, and Roberts, Space Threat Assessment 2018, 1.
27
Todd Harrison, “The Risks a War in Space Poses for Nuclear Stability on Earth,” in Caroline Dorminey and Eric Gomez
eds., America's Nuclear Crossroads (Washington, DC: Cato Institute, 2019), 30.

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By disrupting communication reliability and interfering with access to radar technology, satellite jamming could
also degrade the speed at which an opponent could collect and act on information.

Risk Factors for Strategic Stability

Jamming can be action-enabling due to its ability to heighten situational awareness relative to an adversary. By
disrupting an opponent’s ability to monitor, communicate, and coordinate forces across a conflict theater by
jamming communications and GPS satellites, for example, satellite jamming would reduce the opponent’s
understanding of the battlefield and ability to react.

As such, jamming capabilities pose a short-term risk to crisis stability due to their ability to provide a first-mover
advantage. By disabling the communications and GPS capabilities that allow a state to project force in response
to another’s military action, they could sufficiently weaken an adversary’s short-term ability to effectively
respond. With less reliable information about the actions of the first-mover and fewer conventional capabilities to
counter those actions, escalation could be more likely.

In this sense, jamming capabilities present a risk to strategic stability in that they could embolden an offensively-
minded state to act more aggressively. For example, the U.S. Army reports that the maneuver brigades of the
Russian Ground Forces (RGF) maintain large electronic warfare companies that are capable of jamming and
disrupting communications, GPS, and ground, airborne, and maritime radars at a range of up to 300
kilometers.28 In a hypothetical invasion, such capabilities could be used to impede an opposing state’s
communications and lower their sensors’ ability to detect aircraft or missile launches, offering significant
advantages. More concretely, after losing multiple aircraft to Georgian air defense systems in the first phases of
Russia's 2008 invasion of Georgia, the RGF deployed ground-based jamming platforms that significantly tilted
the balance in their favor.29

Outside of open military conflict, jamming capabilities offer additional advantages relative to other ASAT
weapons. Kinetic ASAT weapons are highly destructive, with irreversible effects on their targeted satellite or
ground station. They tend to be easily attributable because many states can identify the source of kinetic ASAT
attacks; the launch of direct-ascent weapons is traceable, and the orbital data of a co-orbital weapon can usually
be tracked back to its initial deployment.30 A successful attack would be known to both parties immediately as
well because it would produce debris and other physical damage.31

However, unintentional satellite interference is very common. Even in cases of deliberate satellite interference,
jammers can be hard to pinpoint because they can be highly mobile and intermittent in operation.32 They can
also blend in with commercial systems such as uplink news vehicles, appearing harmless.33 Even if found, due
to the size of less sophisticated jamming equipment, the technology can be placed in a population center or in a
third country where an adversary might be unwilling to target it. There is a large offense-defense cost differential

Gen. Morgan J. Spring-Glace, “Return of Ground-Based Electronic Warfare Platforms and Force Structure,” Military
28 Maj.

Review (July/August 2019): 42, https://www.armyupress.army.mil/Portals/7/military-review/Archives/English/JA-19/Spring-

Glace-Electronic-Warfare.pdf.
29 Ibid., 43.
30
Harrison, Johnson, and Roberts, Space Threat Assessment 2019, 3.
31 Ibid.
32 Wilgenbusch and Heisig, “Command and Control Vulnerabilities to Communications Jamming,” 61.
33 Ibid.

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in favor of satellite jammers, as they are much easier to procure, deploy, and operate than they are to locate
and destroy.

Due to the attribution and detection challenges associated with jamming, it is reasonable to assume that the
likelihood of jamming-related vulnerabilities being exploited is higher than that of kinetic ASAT weapons. 34
Insofar as jamming is reversible and neither kinetic nor publicly visible, it operates somewhere below open
warfare, constituting a “gray zone” tactic that can be used in peacetime without a high likelihood of escalation.
Most simply, if an attack cannot be conclusively attributed in a timely fashion, retaliation is less likely. For
example, Iran has frequently jammed satellite communication broadcasts like the British Broadcasting
Corporation and Voice of America at times of heightened international pressure without major repercussions. 35
North Korea regularly jams GPS signals transmitting into
Jamming operates somewhere South Korea, and Russia has jammed GPS signals during
NATO military exercises.36 In each instance, actors hostile
below open warfare, constituting to the United States and its allies have avoided significant
a "gray zone" tactic that can be retaliatory action.
used in peacetime without a high Until the 1990s, policymakers had long assumed that
likelihood of escalation. adversaries would be deterred from attacking satellites
involved with nuclear command and control. Because
space-systems first evolved during the Cold War to primarily support nuclear systems, nuclear deterrence on
Earth was closely connected with deterrence in space. Nonetheless, today it is conceivable that an adversary
may unintentionally interfere with satellites involved in nuclear systems when seeking only to disrupt
conventional capabilities. Space systems have become heavily integrated with conventional combat missions,
and many satellites that were once solely used to support nuclear forces are now used in conventional missions
as well.37 In nonnuclear conflict, then, an adversary could seek to jam satellites that are being used to support
conventional operations, even if those systems are also used in nuclear command and control.38 Given the dual-
use nature of U.S. space systems, the intentions of an adversary seeking to disrupt conventional capabilities,
but inadvertently interfering with nuclear systems as well, could be misunderstood and lead to escalation
through miscalculation.39

Conclusion
Satellite jamming capabilities decrease certainty surrounding adversary force posture and by consequence have
the capacity to decrease strategic stability. During conflicts, these capabilities may also serve as an “equalizer.”
States with advanced militaries, like the United States, Russia, and China, have much more robust space
systems and rely upon them for command and control. While they provide immense military advantages, they
are also very expensive to develop and operate. Satellite jammers, however, are relatively inexpensive and
require a low technological competency, allowing a wide range of states to disrupt superpower operations.

34 Harrison, Future of MILSATCOM, 14.

35 Kathleen H. Hicks et al., By Other Means: Campaigning in the Gray Zone (Washington, DC: CSIS, July 2019), 11.
36
Harrison, Johnson, and Roberts, Space Threat Assessment 2019, 33; Hicks et al., By Other Means, p. 9.
37 Harrison, “The Risks a War in Space Poses for Nuclear Stability on Earth,” 32.
38 Ibid., 34.
39 Ibid.

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Furthermore, given that satellite jamming does not cause permanent physical damage and that timely attribution
can be difficult, the escalatory potential is relatively low.

Nonetheless, if these capabilities were used pre-emptively and were highly effective at rendering large parts of
U.S. space systems inoperable, they would ultimately leave the United States with fewer conventional options to
respond. And since many satellites now assist with nuclear command and control as well as conventional
missions, it is possible that nuclear capabilities could be inadvertently degraded by adversaries seeking only to
disrupt conventional missions. Miscommunication and escalation could then become more likely, especially in a
crisis scenario.

Still, advanced militaries are developing multiple techniques to ensure satellites are highly resistant to jamming
technology. Jamming capabilities could be highly disruptive, but more often, they constitute another “gray zone”
tactic operating somewhere below the threshold of open war.

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