hank rausch jamming paper

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Jamming Commercial Satellite Communications During Wartime:

An Empirical Study

Hank RauschCACI, Inc

[email protected]

Abstract

Satellite Communications parameters—Carrier to Noise

Ratio, Bandwidth, Power, and Frequency—wererecorded for approximately 500 satellite communication

carriers continuously, over a period of 16 months.

These carriers support communications for militaryoperations in the current Iraq war. Communications

outages during this period were logged and the reason

for outage was determined. Some outages caused by

electromagnetic interference are shown to havecharacteristics that would be expected if these carriers

were being subjected to a hostile denial of service

attack. Keywords: commercial satellitecommunications, jamming, denial of service attack,

hostile interference.

1. Overview

Commercial satellite communications play anincreasingly vital role in military operations. During

Operation Desert Shield/Desert Storm (1990-91),

military use of satellite communications was 1 Mbps per

5000 combatants. By Operation Iraqi Freedom (2003),this ratio had increased to over 51 Mbps per 5000

soldiers [1]. Other sources put the figure at 3,200

Mbps for 132,000 combatants in Iraq today, for a ratio

of 121 Mbps per 5000 combatants [2]. Simply put, itwould be impossible to conduct modern warfare as it is

done today without commercial satellite

communications. This stems from two unrelated trends:(1) The evolution of command and control mechanisms

to ever smaller units of action, creating exponential

growth in the numbers of communications links

required to sustain operations; and (2) inadequate procurement of military satellite communications,

which failed to keep up with the burgeoning demand.

These two factors explain why today, 84% of satellitecommunications supporting operations in Operation

Iraqi Freedom is provided by commercial satcomm [3].

This reliance on commercial satellites—leasedtransponders from Intelsat and Eutelsat, for example—

brings with it an attendant vulnerability. These satellites

are not hardened to protect against maliciousinterference, or jamming. The potential exists that vital

military communications could be severed or reduced at

a critical time, due to unauthorized transmission to thesatellite by an adversary. Recent authors have

highlighted this vulnerability, specifically as it relates to

the military’s use of commercial satellites [4]. TheCongressional Research Service makes this point

explicitly in a recent report to Congress:“…a growing dependence on space

communications may also become a critical

vulnerability for Net-Centric Warfare” [3].The potential for this type of attack is known and

has been acknowledged [5], but up to now empirical

evidence for it has been lacking.This paper presents empirical evidence of all types of

interference, including that by suspected hostile

adversaries, observed during ongoing operations inOperation Iraqi Freedom (OIF). As a contractual clause

in the provision of leased satellite bandwidth to the U.S.

military, it was required to monitor and record the

spectral shape, power level, and carrier to noise ratio ona continuous basis for all commercial transponders

leased to the military. This data was collected from

July, 2004 to November, 2005 and all instances ofdegraded communications catalogued and analyzed.

The evidence suggests that unauthorized interferenceis a small but significant subset of all types of satellite

communications problems experienced. Within this

subset, the cause of the majority of interference events

Proceedings of the Fourth IEEE International Workshop on Information Assurance (IWIA’06)

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was eventually found and determined to be non-hostile.However, in a subset of these interference events the

cause could not be determined. Furthermore, these

events all had similar “attack profiles,” and in all cases

they disrupted military communications, forcing units torelocate their communications to another satellite,

another transponder, or a different part of the sametransponder. It is reasonable to deduce that at leastsome of these events were in fact hostile

communications denial of service attacks. This paper

presents an analysis of these attacks, and concludes with

a consideration of ways to mitigate this type of attack.

2. Background

Commercial geosynchronous communicationsatellites are susceptible to a denial of service attack by

hostile electromagnetic interference. This interference

can be present at the local receiver (downlink jamming),or directed at the satellite and mixed with or overriding

the valid carrier (uplink jamming). Downlink jamming

is relatively easily detected and dealt with, using

traditional direction finding and triangulationtechniques. Uplink jamming, on the other hand, is both

easy to conduct and harder to prosecute.The vulnerability of commercial satellites to uplink

jamming lies in the nature of their construction and

operation: A transponder on the satellite accepts

microwave energy within a specified range andretransmits it at the downlink frequency. No special

processing or filtering is done; the transponder acts as a

simple repeater. Consequently, if a foreign signal of the

appropriate carrier frequency is introduced, it is

retransmitted along with any legitimate signals that are present on the transponder. If the foreign signal is of

sufficient carrier to noise ratio, a receiver attempting todetect and demodulate the legitimate carrier will be

unable to do so, as the two signals are mixed. The

foreign signal also raises the noise floor of thattransponder, which in turn reduces the carrier to noise

ratio of all legitimate carriers. Since most small aperture

satellite receive sites are (in general) receive powerlimited, this foreign signal may degrade or sever all

communications on the transponder, even in cases

where it does not directly mask the legitimate carrier.This effect is intensified by the tremendous encoding

gain employed in current commercial satellitecommunication modulation protocols. The effect ofcurrent encoding techniques is that a small decrease in

carrier to noise ratio—in some cases only 1-2 dB,

results in complete cessation of effectivecommunications, from what was once an essentially

error-free channel. Finally, an additional artifact of

commercial satellite communications is that since theyare geostationary, they are easily targeted with

rudimentary equipment. No tracking equipment is

needed; it is only necessary to transmit on thedesignated carrier frequency with a continuous wave

(unmodulated) signal at the elevation and azimuth for

the target satellite.The power required to degrade or sever

communications depends on the carrier to noise ratio of

the signal being targeted. Broadcast communications

carrier signals generally have carrier to noise ratios of20 dB or more. Consequently, degradation of these

carriers would require transmit equipment of a like

nature—antennas of large aperture—9m or more—and

power amplifiers rated in the thousands of watts.Indeed, all documented cases of interference with a

commercial broadcast have involved anothercommercial broadcast site. In a series of attacks

between 23 and 30 June, 2002 the outlawed cult Falun

Gong successfully broadcast over 10 channels being

aired by Chinese TV on Sinsoat-1. They did this fromTaiwan, using a commercial broadcast site [6].

In 1986 a disgruntled satellite dish vendor and part-time teleport operator, John MacDougal, broadcast over

HBO’s satellite service on Galaxy 1 for about 4

minutes, dubbing himself “Captain Midnight”. He used

the 30 foot dish at Florida’s Central Teleport, where heworked part-time, to do this [7].

During the period July 6 to July 14, 2003, Voice of

America broadcasts to Iran were suspected of being jammed by Cuban authorities [8].

So in general, disruption of a high power broadcastservice requires like equipment. This is not the case for

full duplex point to point communications using so-called Very Small Aperture Satellite Terminals(VSATs). These terminals typically use antennas

varying in size from about 1 meter to several, usually a

maximum of 4 meters. Because they are easy to set upand tear down, they are used for the majority of ad-hoc,

semi-permanent communications needed by U.S. Forces

in land operations. These terminals are almost alwaysreceive-power limited. Typical carrier to noise ratios are

in the range of 6 to 10 dB above the noise floor,

depending on weather conditions. Typical transmit

power is a few watts. Depending on the bandwidth ofthe targeted signal, an interfering signal only needs to be

(approximately) one-half powerful as the target signal tocompletely disrupt communications. Recall that due to

advanced coding techniques, the effect of decreasingsignal to noise ratio beyond a certain threshold is

effectively complete cutoff. This can be done with a

comparable VSAT with comparable power supply asthe victim terminal.


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The extent to which VSAT terminals are vulnerable

to this type of interference is shown by the large number

of instances of unintentional self jamming that occur in

military use of commercial satellite bandwidth.Commercial satellites all use polarization separation to

maximize the use of available carrier bandwidth.

Typically, communications are carried outsimultaneously on identical carrier frequencies, on both

the horizontal and vertical polarizations. A vital step in

setting up a terminal for allowed transmission is to zero

out the “cross polarization” component of one’sterminal, by rotating the transmit feed horn. Failure to

do this properly results in excessive power on the other pole, presumably being used by other customers.

Military satellites, in general, do not use polarization

separation, and consequently many military terminaloperators are unaware or unappreciative of the

significance of minimizing cross polarization. In

military use of commercial satellites, it is commonplaceto have to respond and attend to several cases a week

where a terminal is inadvertently cross-polarized. Inshort, the user terminals act as jammers themselves,

operating at their normal transmit frequencies and powers. This illustrates how easy it would be to do so

on purpose.Uplink jamming is made an even more significant

threat by the fact that a threat jammer can be anywhere

in the uplink footprint of the transponder, potentiallythousands of square miles. This threat can be made even

more difficult to eliminate because the jammer can be

mobile, or operate only on a limited duty cycle, or both.Geolocation of the threat jammer while he is on the air

is made difficult due to the directional nature of the

uplink transmission—it does not broadcast out in a wide pattern, as would a downlink jammer. Rather, it

concentrates its energy in a focused beam, making it

very hard to triangulate.Susceptibility to this sort of information warfare has

been understood in the abstract for some time.However, to date there has been little documentation of

actual attacks using these techniques. It is proposed

here that one reason for this lack of documentation is

that it is difficult to isolate bona fide interference attacksfrom other forms of communication degradation in

general, and specifically from other forms of

interference. Contributing to this difficulty is the fact

that commercial satellite providers do not monitor alltheir transponders all the time, and that even when they

do they almost never record and archive transponder or

carrier characteristics. Consequently forensic analysisof past suspected attacks has been impossible.

Fortunately, it is now possible to analyze at least asubset of the commercial satellite bandwidth used for

military communications, and to make an assessment of

the relative threat of hostile interference, or uplink

jamming. This is so because for a significant portion of

commercial bandwidth provided during the current Iraq

War, a contractual clause stipulated that these

communications be monitored and the RF parametersrecorded continuously. This dataset provides us with an

opportunity to investigate and determine whether

instances of jamming occurred. The evidence is only

circumstantial, in that it is not possible, in the absenceof information about the transmitter in these instances,

to definitely say that jamming was occurring. However,

we can certainly determine that communications wereimpacted, and that the nature of interference conformed

to how an attacker would be expected to behave.What follows is an analysis of all instances of

communications degradation that occurred during the

period July 2004 to October, 2005. This set of events iscategorized according to source, leaving a subset caused

by interference. This subset of interference events is

further classified according to origin. A subset ofunknown interference events, all of which severely

degraded communications, is then analyzed for theirsimilarity to what would be expected to be a traditionalattack profile.

3. Data Gathering

Leased commercial satellite transponders were

monitored as part of a contractual requirement in the provision of commercial satellite services to the U.S.

military. This was done by a worldwide network of

teleports with receive antennas located in the downlinkfootprint of the leased transponder. A spectrum

analyzer was connected to the Low Noise Block

Downconverter (LNB) or Low Noise Amplifier (LNA)of each antenna. The signal was digitized, and each

carrier attribute—power level, carrier to noise ratio,

occupied bandwidth, and center frequency—wasrecorded. These values were compared to expected

values, and an alarm created at a central monitoring site

when measured values differed significantly. Inaddition, alarms were also generated if an unexpected

carrier appeared. In most cases these alarms were due

to an authorized site transmitting without priorcoordination with the satellite provider, but in a subset

of these cases the source of the unauthorized carrier was

unknown. In these instances, detailed spectral plots of

the interference were taken and all efforts were made todetermine the source, and to restore communications.

A screen capture of a monitored carrier, with parameters

monitored, is shown in Figure 1.


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Figure 1: Monitored carrier with parametersshown

The scale of these monitoring operations is quitelarge, involving (to date): 16 worldwide teleport sites,some 46 separate monitor antennas, over 100 discrete

transponders, and over 500 individual carriers. The

volume of data collected is therefore huge, consisting ofover 7M discrete parameters recorded since monitoring

operations began in April 2003. This information is

stored in a database, along with records of each alarmand actions taken to correct the alarm. It is this body of

data that is the source for this study. The study focuses

on a subset of this data collected from July, 2004 to November, 2005, when detailed records of

troubleshooting efforts were retained.

4. Results

To understand the scope of the problem ofunauthorized communications interference, and

specifically potentially hostile attacks, it is useful to

categorize first all alarms, then the subset of thesealarms caused by unauthorized interference, and then

the subset of these events for which the source is

unknown and deemed potentially hostile.Figure 2 shows the average number of carriers

monitored per month. It can be seen that the number of

carriers monitored increases each month, which itself is

further evidence of the increasing reliance of militaryoperations on commercial satellites. The vast majority

of these carriers provided communications in support ofOperation Iraqi Freedom (>80%), but also included here

are communications supporting operation in other

theaters. These carriers were generally several Mbps in bandwidth and constituted one-half of a full duplex

point to point communications link, but range from a

few tens of kHz to 27 Mbps. Modulation also varies,with the vast majority being Single Channel per Carrier

(SCPC) with QPSK modulation, but some broadcast

carriers are included and the data also contains a few

multiple access networks using Time Division MultipleAccess (TDMA). A very few carriers also used spread

spectrum modulation techniques.

0

50

100

150

200

250

300

350

400

450

500

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Figure 2: Average Number of CarriersMonitored per Month (7/04-10/05)

Figure 3 shows the number of alarms created by the

monitoring system during this time period. In fact, thenumber of actual alarms is much higher, this chart

represents the number of trouble tickets opened. To

reduce operator workload, trouble tickets are createdonly when a carrier exceeded nominal parameters for a

set amount of queries (usually within a six minute

period). This chart shows that satellite communicationsare subject to many types of problems, most of which

are transitory and correct themselves quickly.

0

500

1000

1500

2000

2500

3000

3500

1 2 3 4 5 6 7 8 9 1 0 11 12 13 14 15 16

Figure 3: Alarms per month for monitoredcarriers

Figure 4 shows the subset of the alarms indicated inFigure 3 that were actual problems that were tracked

over a period of time to resolution, in the same time

period (7/04-10/05). It can be seen that the number of problems tracked to resolution is much smaller—on the

order of 50 times less—than the number of alarms

generated by those carriers. The reason for this is thatmany alarm conditions are transitory and correct

themselves before troubleshooting efforts are required.

It is possible that the alarms shown in figure 3 containsome hostile interference events, but because the effects


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were so brief, further troubleshooting was not done. So

figure 4 provides the best picture of events that

terminate or degrade satellite communications long

enough to be a real problem.

0

10

20

30

40

50

60

70

1 3 5 7 9 1 1

1 3

1 5

Figure 4: Satellite communications problemsper Month

Not all of these events are unauthorized interference,in fact, these events are a minority. This can be seen infigure 5. Figure 5 is a breakdown of all problems

identified in figure 3 according to cause. Causes are

categorized as follows: End of Mission (EOM)*

(13.2%), Hardware Related (HW) (23.0%),Maintenance (M) (15.7%)**, Power (P) (16.9%),

Weather (Wx) (14.5%), Interference (I) (9.8%) and

Unknown (U) (6.9%).

*End of Mission refers to the condition where a carrier

has gone off the air apparently for no cause, and it wassubsequently determined that the transmit station

intended to do so but did not notify the satellite provider

beforehand, and troubleshooting efforts were initiated.

**Maintenance refers only to those cases where a

station went off the air for maintenance withoutnotifying the satellite provider. Scheduled maintenance

with prior notification did not trigger an alarm.

eom

hw

int

main

pwr

unk

wx

Figure 5: Classification of satellitecommunication problems according to cause

In summary, only 9.8% of satellite communications

problems for the monitored carriers were due to

unauthorized interference. This represents a total of 50

separate cases over the monitoring period. In themajority of these cases, it was possible to determine a

cause for the interference.

In the subset of 50 cases of interference where

communications is terminated or degraded, it was

possible to determine the cause for 29 cases. Theresults of this classification are shown in Figure 6. In

12 cases the cause of the interference was a terminal

that was authorized to transmit to the satellite but had animproper polarization setting and therefore was bleeding

energy into the opposite pole (Cross-polarization, or

Xpol.) Fortunately, it is easy to spot the offender sincea cross polarized terminal will have some (usually the

bulk) of its energy on the correct pole, so identification

of the interference source is not an issue. This is not thecase with the other sources of interference. In 3 of the

cases the source was adjacent satellite interference,where carriers on the adjacent satellite bleed onto oneanother. Terminal operators inadvertently transmitting

on the wrong frequency or pole caused 5 cases,

oftentimes because they did not receive the currentlineup (Lineup problems). Some type of self-

interference caused 5 other cases, where a lineup or

equipment problem at the operators own terminal

generated RF energy that interfered with his receivesignal. 3 cases were caused by known events that are

not captured by the above classification.

ASI

Lineup

Other

Self

Unk

Xpol

Figure 6: Classification of interference eventsaccording to origin

This leaves 21 cases during the monitoring periodwhere the interference degraded or terminated military

communications and for which the cause was unknown.A breakdown of these events according to geographic

region is shown in figure 7. Certain common attributes

of these cases makes one infer that it is possible that ahostile operator intentionally caused the interference.

For starters, 15 of the 21 documented cases interfered


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with reception by a terminal in Southwest Asia.

Secondly, in almost half (9 of 21), the cause was

documented as a continuous wave (CW) carrier, i.e. an

unmodulated one. This is significant as in general thereis little reason to ever intentionally transmit a CW

carrier, in fact satellite operators frown on allowing its

use. The reason is that a narrowband CW carrier canhave a much higher carrier/noise ratio than a modulated

one, and thus can easily raise the noise floor of an

authorized carrier to the point that authorized

communications are terminated. In effect, it is the perfect jammer. During normal operation the only time

a satellite operator will allow a CW carrier to betransmitted is during initial lineup of the terminal.

0

2

4

6

8

10

12

14

16

SWA Eur ope CONUS PAC

Total Unk Interf er ence

Sweeping Carr ier s

CW carr iers

Figure 7: Classification of unknown origininterference events according to geographic

region and characteristics

Furthermore and most damningly, in 5 of the 21

cases, the unauthorized carrier varied its center

frequency within a set band—a “sweeper”.Significantly, every single one of these events occurredto carriers where the receive terminal was in Southwest

Asia. The behavior of a sweeping CW carrier can be

seen in figure 8. This is an actual screen capture of asweeper in action. The lighter trace is the “maximum

hold” trace of the spectrum analyzer, showing a

historical record of the highest amplitude recorded bythe spectrum analyzer in that frequency. The darker

trace shows the current (real time) trace. A narrowband,

high C/N CW carrier can be seen at approximately 11.1

kHz, and the max hold trace shows that in the past, ithas swept out approximately the upper 15 Megahertz of

the transponder. Users attempting to receive a signal onthis part of the transponder would experienceintermittent outages when the sweeper transmitted on

the same frequency. This is indicative of potential

jammer behavior. For a given amount of power

available at the transmit antenna, it is more effective toconcentrate that power in a high C/N unmodulated

carrier than spread it across a wider spectrum.

Figures 9a through 9c show the temporal behavior of

another sweeping carrier.

Figure 8: Example of a sweeping interferingcarrier

Figure 9a: Example sequence of a narrowbandsweeping carrier t=0

Figure 9b: Example Sequence of NarrowbandSweeper, t= +25 minutes


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Figure 9c: Example Sequence of a NarrowbandSweeper, t=+57 minutes

The ticketing system that recorded these events givesa rough estimate of the duration of impact of these 21unknown interference events. Duration of tickets ranges

from 0.1 hours to two extremely long tickets (2446 and

2043 hours). Throwing out these two instances—thetickets were probably kept open past the time the event

cleared—reveals an average event duration of 85 hours.

In some cases, the sweeper or unauthorized carrierwould stop transmitting and then retransmit again. In

one case, a sweeper’s behavior was quite regular,

always starting at the same time each morning,transmitting along a swept frequency for about an hour,

and then ceasing until the next day.

This behavior: Unmodulated, high C/N signal,sweeping out a section of a transponder, and

intermittent operations, are all consistent with the pattern that would be expected if an adversary were

attempting to disrupt communications. Combined with

the fact that the vast majority of these cases occurred to

communication supporting military operations inSouthwest Asia, it is reasonable to deduce that at least

some of them were due to hostile interference. This

supports the central thesis of this paper, that militarycommunications across commercial satellites are subject

to hostile interference that is relatively easy to execute

and difficult to troubleshoot. The next section will

address ways to defend against this type of attack.

5. Conclusions

The following mitigations are recommended by this

study:

5.1 Monitoring

An active monitoring program for military

communications over commercial satellites is virtually a

necessity. The logged data available for this study wasonly available due to a specific contractual requirement

to monitor and archive leased bandwidth. Commercialsatellite operators do not archive their transponder dataand in many cases do not monitor it continuously at all.

Without a monitoring program, the root cause of many

of the problems highlighted in this study would have been unknown.

Given the difficulties in maintaining satellite

communications highlighted in this study, even withoutthe prospect of hostile interference, it should be clear

that continuous space segment monitoring of

commercial satellite communications is a necessity.

5. 2 Operations Security

The 500+ currently monitored carriers represent afraction of the total number of carriers on commercial

satellites. Even if the range of potential target carriers is

limited to those commercial satellites with the correct

longitude to support communications in a given theater,the choice of potential satellites may be in the dozens

and the number of transponders up to the 100+ range.

The data from this study suggests that an adversary can

disrupt communications on only a portion of atransponder at time. Given the range of potential

transponders to choose from, how does he/she knowwhich one to jam? This highlights the absolute

necessity of keeping the transmission plan that

documents communication parameters secure. By theirnature, it is impossible to keep some characteristics of

these carriers secret—in fact the carriers themselves are

in the public domain, inasmuch as they are transmittedin a common medium open to reception by anyone.

However, the communications that these carriers

support, and specifically the military units and locationssupported, must be kept secure. This necessitates a

decoupling or firewall between carrier characteristics

needed for the satellite operator and operational

information that would give an advantage to anadversary.

5.3 Demodulation

It has been shown that the origin of the majority of

interference events (approximately 60%) wereultimately known, and attributed to “inadvertent

jammers”—non hostile players that, out of material

failure or operator error, accidentally interfered withmilitary communications. However, determining which


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interferers are benign and which are potentially hostile

is a time consuming process. The ability to determine

the modulation type and symbol rate of interfering

carriers would significantly aid this process. Forexample, in some cases an operator becomes “out of

sync” with authorized communications plans and

transmits a previously authorized carrier on anunauthorized part of a transponder. His carrier

characteristics—modulation and encoding type, and

symbol rate—are known. The ability to determine that

an interferer has, for example, an 8PSK modulationtype with a symbol rate of 1230 ksps, would greatly aid

the process of determining the source. TDMA carrierscan easily be mistaken for hostile interference, as on a

spectrum analyzer it appears that a narrowband carrier is

sweeping out a section of bandwidth. The ability todemodulate this signal, at least to the point of

determining that it is a modulated carrier and not a CW

—would allow a monitor to concentrate his/her effortson actual hostile interferers. Commercially available

monitoring equipment exists that can perform this typeof carrier characterization. Its use would greatly aid a

monitoring agent in sorting out unintentionalinterference from potentially hostile actions.

6. References

[1] Rayermann, P. Exploiting Commercial SATCOM: A betterway US Army War College 2003

[2] Satellite Industry Overview: Satellites are Critical GlobalInfrastructure. 2005 GSA/FTS Network Services Conference,

15-18 August 2005. Chicago, IL

[3] Wilson, C., “Network Centric Warfare: Background andOversight Issues for Congress”,(2004) Congressional Research Service, June 2

[4] Gansler, J, and Ninnendijk, H. “Information Assurance;

trends in Vulnerabilities, Threats, and Technologies” WorkingPaper published onhttp://www.ndu.edu/ctnsp/IaverMao03.pdf by the NationalDefense University

[5] GAO-02-781:Critical Infrastructure Protection:Commercial Satellite Security should be more fully

addressed.. GAO Report to the Ranking Minority Member,Permanent Subcommittee on Investigations, Committee onGovernment Affairs, U.S. Senate August 2002

[6] Tanner, J. Behind Falun Gong's satellite hack, downloadedfrom http://www.findarticles.com on 10/22/05

[7] The Story of Captain Midnight , downloaded from

http://www.signaltonoise.net/library/captmidn.htm on10/22/05

[8] Johnson, S. “Cuban Jamming Demands A Firm Response”(2003) WebMemo #310 published July 22, 2003 at http://www.heritage.org


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