ROME, July 8 — The shift is happening beneath our feet, or rather, above our heads. GPS jamming, once a niche concern for military planners, is now a recognized critical infrastructure risk, and the race to build a backup system is accelerating. The fundamental problem is stark: the signals from those satellites arrive on Earth with the power of a 20-watt light bulb from 20,000 km away.
That makes them extraordinarily easy to drown out. Deliberate interference comes in two forms.
Jamming is the brute-force approach — blasting radio noise on GPS frequencies to knock out reception over a wide area. Spoofing is more insidious: it transmits fake GPS signals, tricking receivers into calculating entirely wrong positions and times. Both have been documented in active conflict zones.
Reports place GPS jamming in Ukraine dating back to 2014, and similar incidents have been recorded across the Middle East.
The Known Threat Landscape
The scale of the problem is not theoretical. In 2017, the U.S. Coast Guard logged over 200 instances of GPS interference in the Black Sea region. The U.S. Department of Homeland Security has formally identified GPS disruption as a risk to critical infrastructure.
The U.S. government has not been idle. The Assured Positioning, Navigation, and Timing (APNT) program is underway, explicitly designed to provide backup capabilities.
One promising avenue involves chip-scale atomic clocks. These tiny, highly precise timekeepers, when paired with inertial navigation systems, can keep a vehicle or device accurately positioned without any external signal. The U.S. Air Force Research Laboratory is actively testing these alternatives.
A Terrestrial Comeback
Perhaps the most intriguing development is the revival of a Cold War-era technology. eLoran, a terrestrial radio navigation system, is being modernized by the U.S. Coast Guard. It is a direct descendant of the legacy Loran-C system. Because it operates on a completely different frequency band and uses powerful ground-based transmitters, eLoran is exceptionally hard to jam.
It could serve as a robust, independent backup for both positioning and, crucially, timing. The legislative push for this resilience has been building for years.
The Department of Transportation’s Volpe Center published a landmark report on GPS vulnerability back in 2001. That document, now over two decades old, triggered increased investment in making the system more robust. The momentum culminated in the 2020 National Timing Resilience and Security Act, which directly ordered the Department of Transportation to develop a terrestrial backup system specifically for GPS timing.
