Satellite navigation systems provide positioning, navigation and timing data essential for modern economies—from air transport, shipping and trucking to global finance, where accurate timestamps synchronise banks and exchanges. If GPS signals were cut off for 24 hours, the costs to the British economy alone would come to about £1.4bn ($1.9bn), according to a 2023 government report.
The Global Positioning System was designed for America's armed forces in the 1970s, made available to civilians during the 1980s and declared fully operational in 1993. President Bill Clinton fully opened GPS to civilian use in 2000, transforming it into a free global utility. The system uses 32 satellites orbiting 20,200km above Earth, each carrying radio transmitters with roughly the power of a fridge light-bulb. Years of under-investment have left it vulnerable. The system is supported by just 11 ground stations. An upgrade meant to replace 1990s-era technology offered only modest improvements in accuracy, leaving GPS lagging behind both BeiDou and Galileo. A 2024 report by the Government Accountability Office noted that America has taken more than 20 years to deploy M-code, a jam-resistant military signal that is still not fully operational. America's communications regulator said in March 2025 that it would explore alternatives to GPS.
In August 2025 America launched Navigation Technology Satellite-3 (NTS-3), the first GPS test satellite sent into space since 1977. Its results will inform the design of the next generation of GPS satellites, GPS IIIF, due to begin launching in 2027. NTS-3 is equipped with a transmitter that concentrates the military M-code signal into a "spot beam" covering an area a bit smaller than Texas. Lockheed Martin, which is building the GPS IIIF satellites, says the new signals will cut through roughly 60 times more jamming power than today's can manage.
NTS-3 is also testing CHIMERA, an anti-spoofing system that inserts secret watermarks into GPS signals at certain intervals. Follow-on signals reveal the transmission times of those watermarks, allowing receivers to verify that signals have travelled from a distant orbit rather than from a nearby spoofer. The satellite additionally tests running two atomic clocks simultaneously, rather than keeping back-ups cold—warming up a back-up clock can take a satellite offline for days.
The ground-control software for the upgraded system, known as OCX and developed by RTX (formerly Raytheon), was delivered to the Space Force in July 2025 after years of delays. Its $3.7bn cost could more than double by the time testing is complete.
China's BeiDou system is provided by 56 satellites—nearly double the number serving GPS—and supported by 120 ground stations. Unlike GPS, which relies solely on satellites in medium-Earth orbit, BeiDou operates across three orbital layers, giving it wider and more stable coverage. China has also built nearly 300 ground-based backups, fibre-optic networks to transmit accurate timing information, and an eLoran system—a ground-based alternative that uses powerful transmissions more difficult to jam than weak satellite signals. BeiDou is designed to be compatible with GPS, owing to an interoperability agreement signed in 2017, which also means China can easily mimic GPS signals for spoofing purposes.
BeiDou is being embedded in Chinese-built infrastructure such as phone networks, power grids, ports and railways constructed under China's Belt and Road Initiative. Pakistan and Saudi Arabia are using it to replace GPS in some defence applications. Some devices are locked into using only BeiDou, creating dependencies. Dana Goward, president of the Resilient Navigation and Timing Foundation, has warned that "BeiDou gives China an on-off switch for countries that rely on it."
A European alternative to GPS. Britain briefly considered launching its own satellite system after Brexit reduced its access to Galileo, but balked at the cost. Instead it is building a cheaper backup using atomic clocks, fibre-optic cables and eLoran transmitters and is testing quantum sensors.
Russia's satellite navigation system.
Because GPS signals are extremely weak by the time they reach the ground, opponents can drown them out by broadcasting more powerful ones. Jamming has become a constant feature of the electronic warfare on the front lines in Ukraine. Spoofing—replacing the signal with a misleading one—is also widespread; pilots and ship captains regularly report it, especially in the Middle East and near Russia. GPS still uses radio signals designed in the 1970s whose details are public knowledge, making them easy to copy using cheap software-defined radios. BeiDou and Galileo, by contrast, can have their signals tweaked by software updates beamed from the ground, making spoofing harder.
Large-scale jamming and spoofing of GPS in or near war zones have exposed the fragility of satellite navigation. Russia and China are investing in technologies capable of jamming GPS on a massive scale. In a conflict over Taiwan, China could jam or spoof GPS signals across the Taiwan Strait, disabling navigation for American and Taiwanese forces, while its own alternative systems—particularly eLoran—would remain largely unaffected.
Few countries can afford to create a global navigation system, so most rely on GPS, BeiDou, Galileo or GLONASS. South Korea and Japan are developing their own regional solutions.
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