Electronic Warfare and GPS Denial: Fighting in a Contested Spectrum

Nearly every capability a modern military depends on runs through the electromagnetic spectrum. Communications, navigation, targeting, intelligence collection, and the control links for the drones now dominating tactical combat all require the spectrum to be usable. It increasingly is not.

Jamming, spoofing, meaconing, and sustained radio-frequency pressure are now baseline operating conditions rather than exceptional events. GNSS interference has become a constant of modern conflict rather than a periodic occurrence. GPS jamming over Ukraine has been severe enough to create what researchers described as a giant hole in GPS coverage for small satellites in low Earth orbit carrying onboard receivers — interference from the surface degrading space-based reception.

The operational consequence is straightforward: an assumption of GPS availability is no longer a valid planning assumption anywhere near a peer or near-peer adversary. Systems, doctrine, and training built on that assumption require rework.

The threat taxonomy

Precision about what is being done to the spectrum matters, because the countermeasures differ.

Jamming transmits noise or structured interference on the frequencies a receiver depends on, raising the noise floor until the signal becomes unusable. Against GNSS this is trivially easy in energy terms — satellite signals arrive at the earth's surface below the thermal noise floor, and a modest transmitter can deny reception over a substantial area.

Spoofing transmits counterfeit signals that a receiver accepts as genuine, producing a false position or time solution. More sophisticated than jamming and more dangerous, because the victim does not know it is being deceived. A spoofed aircraft or munition proceeds confidently to the wrong place.

Meaconing intercepts and rebroadcasts genuine signals with delay, producing position errors without generating counterfeit signals. Harder to detect through signal authentication because the signals are authentic.

Communications jamming targets tactical radio, satellite communications, and datalinks. Against drones, this is the primary counter-UAS mechanism in current use.

Electronic support — detecting, characterizing, and geolocating emissions — is the passive side and increasingly the more consequential one. Any transmission is a targeting cue. Emission control discipline has returned as a survival requirement.

Why GNSS is inherently vulnerable

The vulnerability is structural, not a design defect that can be patched.

GNSS signals originate from satellites in medium earth orbit approximately 20,000 kilometers away. By the time they reach a receiver, signal power is extraordinarily low — roughly 10^-16 watts. The receiver recovers them using spread-spectrum processing gain.

A jammer a few kilometers away transmitting a few watts overwhelms that signal by many orders of magnitude. The physics is not close. No amount of receiver improvement changes the fundamental power asymmetry between a distant satellite and a nearby transmitter.

Military GNSS signals — encrypted, with higher power and better anti-jam waveforms — improve the margin substantially but do not eliminate it. M-code and its equivalents raise the required jamming power but remain deniable at sufficient jammer strength or proximity.

This is why the entire assured positioning, navigation, and timing enterprise focuses on alternatives and complements rather than on hardening GNSS alone.

Assured PNT: the response

The U.S. Army is pursuing two programs of record: the Dismounted Assured PNT System (DAPS) for individual soldiers and the Mounted Assured PNT System (MAPS) for vehicles, with the Program Executive Office for Intelligence, Electronic Warfare and Sensors responsible for fielding.

The architectural principle is layered defense in depth rather than a single solution.

Antenna-level protection. Controlled reception pattern antennas use multiple elements to null interference arriving from the direction of a jammer while preserving reception from satellites overhead. Highly effective against a small number of jammers, degrading as the number of interference sources increases. Adds size, weight, power, and cost.

Receiver-level protection. Multi-frequency, multi-constellation receivers using GPS, Galileo, GLONASS, and BeiDou simultaneously force a jammer to cover more spectrum. Advanced signal processing detects and excises interference. Anti-spoofing techniques compare signal characteristics against expected values and flag inconsistencies.

Inertial navigation. An inertial measurement unit using accelerometers and gyroscopes is entirely self-contained and cannot be jammed by any external signal. Its limitation is drift — error accumulates over time without external correction. Tactical-grade units drift meaningfully within minutes; navigation-grade units maintain accuracy far longer at substantially higher cost. Chip-scale inertial sensors and improved algorithms have made this the workhorse of GNSS-denied navigation.

Alternative navigation sources. Vision-based navigation matching camera imagery against reference data. Terrain-relative navigation. Celestial navigation, which has returned via automated star trackers. Magnetic anomaly navigation using variations in the earth's magnetic field. Signals of opportunity using terrestrial broadcast transmissions. Each has distinct failure modes, which is precisely why combining them works.

Alternative timing. Frequently overlooked and operationally critical. GPS provides precise time to communications networks, electrical grids, financial systems, and frequency-hopping radios. Chip-scale atomic clocks and network time distribution address the timing dependency separately from the positioning dependency.

The design principle across all of this: no single source, and sources with uncorrelated failure modes. A system that fuses inertial, visual, and GNSS degrades gracefully rather than failing catastrophically.

The drone dimension

The interaction between electronic warfare and uncrewed systems has become the defining dynamic of tactical combat.

Small drones depend on the spectrum in three ways: a control uplink, a video downlink, and GNSS positioning. Each is attackable, and electronic attack has been the primary counter-UAS mechanism for exactly that reason — it is cheap, scalable, and effective per engagement.

The adaptations have been rapid and are covered in detail elsewhere, but the electronic warfare implications deserve note:

Fiber-optic control removes the RF link entirely, eliminating both the jamming vulnerability and the emission that makes the operator geolocatable. This is a substantial defeat of the electronic attack layer, and it has invalidated a meaningful fraction of deployed counter-UAS investment.

Autonomous terminal guidance removes dependence on both the control link and GNSS in the terminal phase.

Frequency agility and digital protocols raise the cost of jamming without eliminating it.

The consequence for electronic warfare planners is that jamming can no longer be the primary counter-drone mechanism. It remains valuable — most drones still use RF and most still use GNSS — but a jamming-centric posture is now insufficient against a capable adversary.

Meanwhile the drone density on the battlefield has created a spectrum management problem of its own. Hundreds of simultaneous drone links, friendly jammers, tactical communications, and enemy emissions produce an environment in which friendly systems interfere with each other substantially. Electromagnetic spectrum management has become a genuine command function rather than a technical afterthought.

Operational lessons

Recent conflicts have generated consistent observations.

Emissions are targeting cues. Any transmitter is geolocatable and therefore targetable. Command posts identified by their emissions have been struck within minutes. Emission control discipline, directional antennas, remote antenna placement, and low-probability-of-intercept waveforms have moved from good practice to survival requirements.

Electronic attack is indiscriminate. A jammer denying enemy GNSS also denies friendly GNSS in the same volume. Friendly forces operating in their own jamming envelope need alternative navigation. This coordination problem is consistently underestimated in planning.

Spectrum superiority is local and temporary. No force achieves sustained spectrum dominance across a theater. The realistic objective is local advantage at a decisive time and place.

Adaptation cycles are measured in weeks. New waveforms, frequencies, and techniques appear and are countered continuously. Systems requiring depot-level modification to change parameters are effectively obsolete on fielding. Software-defined, field-reprogrammable systems are the only viable approach.

Interference has spilled into civil aviation. GNSS interference affecting commercial aircraft in conflict-adjacent regions has become common enough to prompt regulatory attention, and it demonstrates that spectrum effects do not respect boundaries.

Beyond Ukraine, similar patterns have appeared elsewhere: during India's Operation Sindoor against Pakistan in May 2025, Indian electronic warfare forces were deployed specifically to interfere with GNSS signals, indicating that GNSS denial has become a standard component of conventional military operations rather than a specialty capability.

Industry and procurement implications

Software-defined is mandatory. Any electronic warfare or PNT system that cannot be reprogrammed in the field to address new threats will be ineffective within months of fielding. This should be a threshold requirement.

SWaP-C dominates at the tactical edge. A controlled reception pattern antenna that works but weighs three kilograms and costs $40,000 will not be fitted to a $2,000 drone. Chip-scale, low-cost anti-jam solutions represent the largest unmet requirement in the field.

Sensor fusion is the differentiator. Combining inertial, visual, celestial, magnetic, and signals-of-opportunity data into a coherent navigation solution with correct uncertainty estimation is a hard software problem and where value concentrates.

Testing infrastructure is constrained. Realistic electronic warfare testing requires spectrum access, anechoic facilities, and instrumented ranges that are genuinely scarce. Simulation helps but does not substitute for live testing against representative threats.

Timing is a separate market. The dependence of communications, networks, and infrastructure on GPS timing is a distinct vulnerability with distinct solutions and a distinct customer set including civilian critical infrastructure.

Dual-use demand is growing. Commercial aviation, maritime shipping, autonomous vehicles, and critical infrastructure all face GNSS interference. Technology developed for defense has a substantial adjacent civil market, which improves the business case for investment.

Outlook

Several trends look durable.

GNSS denial will remain routine and will spread. The technology to jam is cheap, widely available, and difficult to attribute. Any conflict involving a moderately capable adversary will feature GNSS denial as a baseline condition.

Alternative PNT will move from specialist equipment to standard fit. The cost curve for chip-scale inertial sensors, atomic clocks, and vision-based navigation is falling fast enough to make broad fielding practical within a few years.

Cognitive and adaptive electronic warfare — systems that characterize an unknown emitter and generate an effective countermeasure autonomously — is the principal area of development. The adaptation cycle has compressed below what human-in-the-loop reprogramming can support.

Spectrum management will be recognized as a command function requiring dedicated staff, tools, and authority. Current practice treats it as a technical annex, which is inadequate at present drone and emitter densities.

And the assumption that underlies most Western precision warfare — that GPS will be available — will finally be removed from doctrine, training, and requirements. That has been recommended for two decades. Operational experience has now made it unavoidable.

A final observation concerns training. Units that have only ever operated with reliable GPS develop habits, procedures, and staff processes that assume it. When the signal disappears, the degradation is not merely technical — navigation errors, fire support coordination failures, and timing mismatches compound because nobody has practiced the alternative. Several militaries have begun conducting exercises with GNSS deliberately denied across the training area, and the initial results have been consistently sobering: units accustomed to precise position and time perform substantially worse than their equipment alone would predict.

This is a cheap fix relative to hardware. Training in a denied environment costs range time and produces uncomfortable after-action reviews, but it identifies the procedural dependencies that no amount of equipment procurement addresses. Organizations that have done this work report that roughly half the problems they found were procedural rather than technical — map reading, dead reckoning, analog fire support procedures, and manual timing synchronization that had atrophied over two decades of assured GPS availability.

Frequently asked questions

What is the difference between GPS jamming and spoofing? Jamming transmits interference that prevents a receiver from acquiring the satellite signal, causing loss of position. Spoofing transmits counterfeit signals that the receiver accepts as genuine, producing a false position the user believes is correct. Spoofing is more dangerous because the deception is not obvious.

Can military GPS be jammed? Yes. Encrypted military signals such as M-code have higher power and better anti-jam characteristics, which raises the power a jammer must apply, but they can still be denied at sufficient jammer strength or proximity. The power asymmetry between a distant satellite and a nearby transmitter is fundamental.

What is assured PNT? Assured positioning, navigation, and timing — an architecture combining protected GNSS reception with inertial navigation and alternative sources so that position and time remain available when GNSS is denied. The U.S. Army's programs of record include the Dismounted and Mounted Assured PNT Systems.

How do drones navigate without GPS? Through inertial navigation, visual odometry matching camera imagery to terrain or reference data, terrain-relative navigation, and magnetic or celestial references. Most practical systems fuse several of these to compensate for the individual weaknesses of each.

Why can't GNSS just be made jam-proof? Because the received signal power from a satellite 20,000 kilometers away is extraordinarily low, while a nearby jammer can transmit orders of magnitude more power. Anti-jam antennas and processing improve the margin substantially but cannot eliminate a physical asymmetry of that magnitude.