GPS & GNSS, Space Force / global constellation
The world sets its clocks, power grids, financial transactions, telecoms, by the signals of some thirty American satellites, backed up by Galileo, GLONASS and BeiDou. The critical function is not so much position as timing. With extremely weak signals at reception, GPS/GNSS are vulnerable to jamming and spoofing, incidents of which are multiplying in conflict zones.
The hidden dependency: time
GPS is often reduced to the map on a smartphone. Its systemic dependency lies elsewhere: the signal carries an atomic time reference accurate to less than a microsecond, and it is this clock, more than the position, that synchronizes the world's infrastructure. Power grids lock the phase of their current to it; 4G/5G towers synchronize their transmissions on it; financial exchanges timestamp their transactions to the billionth of a second by it; distributed computing depends on it to order its writes. Some thirty American satellites, backed by Galileo, GLONASS and BeiDou, thus synchronize most of the digital infrastructure.
This timing function makes a GPS hazard far graver than a navigation outage. A drift or a prolonged loss does not merely lose cars: it desynchronizes entire networks that, lacking local references precise enough, begin to drop out one after another. The point of failure is invisible because the signal, free and ubiquitous, has been absorbed as an invisible utility.
A signal so weak a pocket jammer suffices
The vulnerability is written into the physics. After 20,000 km of travel, the signal reaches the ground at a power on the order of a femtowatt, weaker than the radio background noise, recovered only through mathematical processing. Covering it therefore takes almost nothing: a jammer the size of a lighter, sold for a few tens of euros, blinds receivers over several kilometers. Spoofing, more insidious, fabricates a false coherent signal that surreptitiously shifts the computed position or time.
What was theoretical has become routine. In 2024–2025, the areas around the Black Sea, the Baltic, the Middle East and Korea saw GNSS jamming and spoofing become widespread, affecting some 1,500 flights a day at the peak and forcing civil aviation to reintroduce fallback procedures thought to be abandoned. Dependence on the signal preceded, by several decades, awareness of its fragility.