Lost in signal: The challenge of GNSS disruptions

In today’s shipping world, modern navigation, port operations, cargo tracking, and numerous communications and automation systems all depend on satellite signals, making them a high-value target in strategic competition. Nation-states use jamming and increasingly accessible spoofing tools to hide movements, disrupt military systems, and deny precision effects, while non-state actors exploit cheap jammers and Automatic Identification System (AIS) spoofing for theft, illegal fishing, sanctions evasion, and opportunistic disruption.

The result is a low-cost, high-impact threat as modest investments in jammers or spoofers can disrupt contested coasts, chokepoints, and busy maritime corridors. Global Navigation Satellite System (GNSS) disruption is no longer theoretical. In the Strait of Hormuz, GPS jamming was reported to have affected over 1,600 vessels in a single day, while Finland’s Coast Guard has tracked persistent interference and AIS spoofing in the Baltic since 2024, including tankers masking port calls in Russia. In the Black Sea and near Crimea, ships have appeared to “sail” across airports, complicating logistics and search-and-rescue operations. Even in calmer waters, GPS or AIS failures in the Baltic and Danish Straits have caused operational delays.

This growing interference has sparked international attention. In March 2025, the International Maritime Organization (IMO), International Civil Aviation Organization (ICAO), and International Telecommunication Union (ITU) issued a rare joint call urging protection of vital radio frequencies and curbs on electronic warfare at sea. Insurers and operators now face higher war-risk premiums, compliance checks, and costly data verification in contested regions.

The human factor

While GNSS technologies have revolutionized the maritime industry, they are far from the first tools used for navigation at sea. For centuries, sailors relied on celestial navigation, using the stars, sun, and moon to chart their course. In more recent times, radar, radio signals, and compass systems played vital roles in guiding vessels. Even the best maritime traditions did not always have instant precision or the ease of one-click navigation. Things like dead reckoning, compass bearings, and visual observations have always been an integral part of the navigation process.

This history reminds us that jamming and spoofing, while a modern and pressing issue, are also a reminder that maritime navigation, at its core, has always faced challenges. What is different now is the scale and sophistication of interference. Modern technology allows for global-scale disruption, making the need for robust safeguards more pressing.

“Technology will keep evolving, but the most reliable defence against GNSS disruption is still a well-trained crew that knows what to do when the blue dot lies. GNSS should be treated as an assistant, not an authority: plan for its failure, rehearse those plans until they’re instinctive, and communicate early when things go wrong,” elaborated Rich.

According to the maritime security expert, bridge teams need to regularly drill loss-of-GNSS scenarios, recognising spoofing, switching fully to manual navigation, and using backup tools with confidence. Good seamanship, not technology, is what carries ships safely through uncertainty: “It is not all doom and gloom. If the industry combines sensible equipment choices with rigorous training and a culture of preparedness, then when satellites falter or deceive, crews will navigate by skill, teamwork, and judgment rather than by relying on a blinking blue icon. At BSM, we believe that regular drills and scenario-based exercises should make GNSS loss a well-practiced, not theoretical, event.”