If you have ever used a smartphone map or watched a delivery vehicle move across a tracking app, you have used GPS. GPS — the US Global Positioning System — is only one part of a broader family called Global Navigation Satellite Systems (GNSS).
Four global satellite systems circle Earth and guide aircraft, ships, cars, trucks and tourists. They also play a central role in war.
How GNSS determines position
GNSS works through time. Satellites carry extremely precise atomic clocks and constantly broadcast two things: their exact orbital position and the exact moment the signal was sent. Receivers on Earth — in phones, cars, planes or ships — pick up those signals. By comparing timestamps from signals from at least four satellites, a receiver calculates latitude, longitude and altitude, and corrects timing errors. GNSS is fast and highly accurate, and deeply embedded in daily life, but it has a hidden fragility: the signals are exceptionally weak and vulnerable to interference.
“Signals from Global Navigation Satellite Systems are quite vulnerable,” says Dana Goward, president of the Resilient Navigation and Timing Foundation. “Any radio noise near their frequency, accidental or malicious, can interfere with reception.”
The four global navigation powers
The first global systems emerged during the Cold War. The US developed GPS, the first to achieve global coverage and now the most widely used. The Soviet Union developed GLONASS. In the early 2000s the EU built Galileo to reduce dependency on US infrastructure. China’s BeiDou is the newest, developed to ensure Chinese military and civilian independence from GPS.
The systems are similar and dual-use — serving civilian and military needs. GPS, GLONASS and Galileo orbit at roughly 19,000–23,000 km; BeiDou adds higher-altitude orbits to strengthen regional coverage over Asia. Each system can reach any point on Earth; many devices use multiple constellations for redundancy. Japan and India operate regional systems that do not offer full global coverage.
GNSS in war and electronic warfare
Armed forces increasingly rely on satellite navigation for logistics, mapping and planning. GNSS guides weapons such as cruise missiles and smart bombs and helps control drones. That dependence makes satellites and their signals valuable targets.
In conflicts like the Russia-Ukraine war both sides have used electronic warfare: jamming, which interferes with signal reception, and spoofing, which feeds false location or timing data to receivers. Spoofing is harder than jamming but can mislead opponents — for example, making a navigation system report being at an airport when the receiver is on a road — and can be used to hide movements or misdirect ships into another country’s waters, creating opportunities for interception.
Vulnerabilities and responses
Because GNSS signals are weak, they are susceptible to accidental or deliberate radio noise. Goward notes that Russia and China have domestic terrestrial backup systems to complement GNSS, while Europe and the US do not, increasing Western vulnerability. There is no single technological fix to neutralize GNSS disruption. Research continues into alternatives and protections, but in active conflict one of the most expedient responses remains locating and destroying jammers.
Edited by: Zulfikar Abbany
