The problem first hit during Russia’s September 2017 Zapad military exercise in its western regions, near the Baltic states. Then it happened again in October during NATO’s Trident Juncture exercise, held in Norway. GPS signals across far northern Norway and Finland failed. Civilian airplanes were forced to navigate manually, and ordinary citizens could no longer trust their smartphones.

During NATO’s Trident Juncture exercise in October, the Norwegian airline Wideroe reported a loss of GPS signal in airplanes flying in the north of the country. At the same time, Finland’s Air Navigation Services, a government aviation authority, issued a similar warning to the country’s airlines. In both places, somebody was jamming GPS systems. Several months earlier, the airport in the French city of Nantes had experienced similar disruptions. The ground-based augmentation system (GBAS) used to assist aircraft during takeoff and landing repeatedly failed, without a detectable mechanical cause.

Nantes’ mystery was solved when airport staff discovered a GPS jammer in the car of a passenger who had forgotten to turn it off before leaving on a transcontinental flight. Norway and Finland had a more serious issue. “It’s a problem that Russia doesn’t respect civilian aviation in the North,” Norwegian Defense Minister Frank Bakke-Jensen told Norwegian national radio.

Armed forces everywhere practice disrupting their adversaries’ navigation. But the nature of GPS makes it an especially vulnerable point—a tool used by both military and civilians, and so potentially fragile that a single culprit, like the contractor at Nantes Airport, can disrupt it.

That doesn’t mean one person can send an airport into meltdown; airlines have backup systems, and pilots are trained to fly manually. But though they’re illegal, jammers are cheap and easily available. “Jamming isn’t very difficult,” noted Mark Dickinson, president of the Space Data Association, an international organization of satellite operators. “While spacecraft are usually well protected, with jamming you can disrupt nearby commercial GPS signals.”

Put in simple terms, jammers overwhelm the receiver with junk signals, preventing the receiver from detecting the real signal. $10 jammers available on the internet can be plugged into a car’s cigarette lighter and jam receivers within a radius of several meters. Most jammer buyers do not intend to cause harm to smartphone users around them, but simply want to trick, say, their boss. But there’s no precision in jamming; block one, block all.

In a war, most of us would have far more serious concerns than calculating a car trip, yet GPS jamming poses a significant threat in its own right.

In a war, most of us would have far more serious concerns than calculating a car trip, yet GPS jamming poses a significant threat in its own right.

Disruptions of daily life are a crucial part of hybrid warfare (sometimes also called grey-zone warfare or threshold warfare). By causing society to grind to a halt, or even just making daily services such as food, medicine or fuel supply, sewage, news media, or the internet function poorly, an adversary can dramatically weaken the target country without moving a single soldier. In recent years the Kremlin has been refining such practices.Armed forces, of course, operate jammers much more powerful than a civilian can easily obtain. And it’s no surprise that Russia should be testing NATO’s capabilities: The Global Positioning System is owned and operated by the U.S. Department of Defense, which provides free access to any civilian with a GPS receiver. That’s a lot of phones. Most smartphones manufactured today are GPS-enabled, and nine in 10 smartphone owners use GPS-supported apps. But Russia operates it own satellite navigation system, GLONASS, as does China, owner of the BeiDou system. The European Union, in turn, operates the Galileo navigation system, which is independent of GPS.

“This is part of a larger Russian pattern of disrespecting norms,” said Charly Salonius-Pasternak, a senior research fellow at the Finnish Institute of International Affairs. “It is, of course, generally understood that in a war everything will be destroyed, and that that has to be practiced. But usually countries don’t do it in such a blatant way.” According to a May 2018 presentation by the National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board, an independent body that advises the U.S. government on GPS, Russia also jammed GPS in Norway and the Baltic Sea in September last year (during its Zapad exercise) and has repeatedly done so in the Eastern Mediterranean. Russian armed forces support Syrian President Bashar al-Assad’s war against rebel forces.

In a war, sabotaging an adversary’s satellite navigation system would deal an enormous blow to its armed forces, which would have to rely on inferior tools. Warships would traverse oceans less accurately, and aircraft would struggle to locate friendly ground forces. But given GPS’s global dominance, such an attack would cause chaos far beyond the military. The cargo ships that carry 80 percent of global trade could find themselves traveling in the wrong direction. They could collide with rocks or other ships. Pilots would have to resort to manual landings. Most ordinary smartphone users would find themselves baffled, with deliveries lost and trips delayed.

That makes GPS spamming a national security concern. Indeed, the National PNT Advisory Board suggests that two of Russia’s goals may be to “encourage adoption and use of GLONASS in lieu of GPS” and to “intimidate its neighbors, cause them to question relationship with/reliance upon US and US technology.”

Russia has also maintained a certain amount of plausible deniability. The Russian Foreign Ministry’s spokeswoman, Maria Zakharova, has accused Norway of accusing Russia of GPS jamming to distract attention from its frigate Helge Ingstad, which sank after a collision at the tail end of Trident Juncture. (The collision appears to have been the result of human error rather than GPS spoofing.) Indeed, Salonius-Pasternak noted, Russia could argue that it’s not responsible for GPS sabotage from its territory: “They can say tourists did it.” These are flimsy excuses, but presenting definite evidence is not only tricky but might expose sensitive information.

A more likely development than revenge jamming is a move to new, jam-secure navigation systems. Earlier this month scientists at the Centre for Cold Matter at Imperial College London presented the world’s first tamper-proof navigation system, a so-called quantum accelerometer, built with funding from the U.K/ Ministry of Defence.

The quantum accelerometer is, however, unlikely to protect civilian users any time soon: it’s primarily designed for nuclear submarines. Everyone else should accept the fact that many of today’s conveniences are, in fact, a luxury—and learn how to live without them in a pinch.