This year's Annual Review reports strong financial results, continued strategic progress and enhanced support for shipowners operating in an increasingly complex and uncertain global environment.
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GPS Jamming, Spoofing and Hacking – what, how and where.
This article will look at the increasing significant risks posed by deliberate acts of jamming, spoofing and hacking. All these practices can have serious implications for navigation systems, including Electronic Chart Display and Information Systems (ECDIS), Radar, and Automatic Identification Systems (AIS). Undermining the ability of the bridge watchkeeper to safely navigate the vessel.
Jamming is the process of intentional interference with GPS transmissions to disrupt the signals that ships rely on for navigation. GPS jamming occurs when a jamming device emits radio signals on the same frequency as GPS satellites which are more powerful than the satellite signal rendering navigation systems ineffective.
Recent incidents highlight the growing presence of GPS jamming, particularly in high-risk areas such as the Strait of Hormuz, Black Sea, Eastern Mediterranean, Red Sea and other regional hotspots.
Such incidents not only complicate navigation but also raise compliance and security concerns, particularly regarding potential sanctions evasion.
Jamming is often linked to military activities, underscoring the geopolitical dimensions of GPS jamming. In the Black Sea, where military operations are prevalent, the risk of collateral damage to commercial vessels is heightened, and maritime advisories have urged caution among ship operators.
Insights into the increase in number of jamming events shared by Windward AI have identified the following trends;
From zero affected vessels in Q4 of 2024 to more than 180 in Q1 of this year and 890 vessels affected in Q2. Anomalies detected off Sudan's coast were possibly linked to increased military collaboration between Iran and Sudan. The interference affected vessel tracking, suggesting strategic efforts to mask maritime activities
Image: Figure 1 - Jamming in Sudan, Windward AI, June 2025.
From 1,225 affected vessels in Q1 of 2025, to more than 5800 affected vessels in Q2.
Finland's Coast Guard reported persistent satellite navigation disturbances. Authorities suspect military sources aiming to protect ports from potential drone strikes.
Image: Figure 2 Jamming in the Baltic, Windward AI, June 2025.
Open-source intelligence in Q4 of 2024 revealed GPS jamming systems near Russia's Gelendzhik port, causing vessels to display incorrect positions, sometimes appearing on land.
Approximately 60 merchant ships experienced GPS jamming off South Korea's west coast, with signals falsely placing them near or within North Korean territorial waters. The disruptions, attributed to North Korean interference, affected vessels anchored at Pyeongtaek and those on route to ports such as Daesan and Seosan.
The average distance vessels “jump” to when their AIS is jammed grew from 600 km in Q4 2024, to a staggering 6,300 km in Q1 of 2025. The signs of jamming include sudden loss of signal and inconsistent position fixes.
Image: Figure 3 Jumps during Jamming, Windward AI, June 2025.
GPS Spoofing occurs when false GPS signals are transmitted to mislead navigational systems. Shipboard systems lock on to the false signal and if not identified by the bridge watch keeper, these can lead to a loss of situational awareness, navigational errors and an increase in the risk of maritime accidents.
Compliance professionals also face challenges in verifying vessel movements accurately as a consequence of GPS jamming and spoofing. This difficulty is particularly pronounced in high-risk areas making it harder to detect illicit activities such as sanctions-busting.
Recent incidents highlight the growing prevalence of GPS spoofing and underscore the need for comprehensive mitigation strategies.
High-profile spoofing incidents have been reported in the Black Sea, where ships' GPS systems showed them located miles inland.
More recently the Joint Maritime Information Center (JMIC) published their latest weekly bulletin dated 17 June noting continued reports of electronic interference in the Strait of Hormuz.
JMIC continues to receive reports of electronic interference stemming from the vicinity of Port of Bandar Abbas, in the SoH and several other areas in the Arabian Gulf”. The diagram opposite identifies those areas most affected.
Image: Figure 4 GNSS Interference Map (source: gpsjam.org) 15/6
Whilst reports of electronic interference across the wider region continue to increase with frequency, reports from the Red Sea suggest an increased intensity that is significantly impacting electronic navigation aids in that area. Vessels are advised to be aware of this interference and navigate with caution.
Image: Figure 5 JMIC Weekly Dashboard 26/5-01/6
The JMIC continues to monitor the situation closely and will provide timely updates should there be any changes. Monitor the UKMTO and MSCIO website for updated information. Daily updates will be provided unless there is a reason to provide more timely information.
To counter the threats posed by GPS jamming and spoofing several strategies can be implemented:
Enhanced Awareness and Training: Vessel operators should ensure that crew are trained to recognise signs of GPS interference. This includes familiarity with navigational procedures to follow when jamming or spoofing are detected, such as cross-referencing GPS data with other terrestrial navigational aids and position fixing techniques.
Adoption of non-electronic position fixing techniques. Visual bearings, Estimated Positions (EPs), Running fixes, Parallel indexing and water depth information can all be used to cross check the accuracy of GPS information, especially in areas where GPS may be unreliable.
Adoption of Advanced Navigation Systems: Implementing multi-frequency and multi-constellation GNSS (Global Navigation Satellite System) receivers can improve resilience against GPS interference. These systems can switch between different satellite networks, reducing reliance on a single GPS source.
Collaboration with Authorities: GPS interference has not gone unrecognised by international agencies with the IMO, ITU and ICAO issuing a joint statement in March this year calling for;
o Protection of the Radio Navigation Satellite Service (RNSS) from harmful interference affecting civilian and humanitarian operations.
o Strengthening resilience of RNSS-dependent navigation, positioning, and timing systems.
o Maintaining conventional navigation infrastructure for contingency support.
o Enhancing collaboration between regulatory, aviation, maritime, defence, and enforcement authorities.
o Implementing comprehensive interference reporting mechanisms.
Operators are encouraged to work closely with flag administration, maritime safety authorities and international organisations to report jamming incidents. This collaboration can facilitate the development of comprehensive strategies to mitigate disruptions.
Legal and Regulatory Framework: While the ITU and ICAO mandate the elimination of harmful interference from GPS jamming, enforcement remains a challenge. Strengthening international legal frameworks and cooperation among nations can enhance the effectiveness of these mandates. IMO’s Maritime Safety Committee, through MSC.1/Circ.1644, has “urged Member States to take actions necessary to minimize interference coming from their territory, as required under the ITU Radio Regulations; States should “consider issuing warning notices or advisories to mariners specifying the time periods and areas impacted by any known interferences to minimize negative effects upon maritime operations; and consider enacting measures that prevent unauthorized transmissions on recognized satellite navigation system frequencies.”
Use of Alternative Technologies: Exploring the incorporation of alternative positioning systems, such as inertial navigation systems or celestial navigation, can provide backup options during GPS outages.
GPS hacking is the unauthorised access or manipulation of a vessel’s GPS based navigation systems.
Unlike jamming or spoofing, which interfere with signals externally, GPS hacking targets the software or systems that process those signals, potentially gaining control over navigation data or system functions.
Hackers exploit vulnerabilities in a ship’s onboard systems to alter GPS data, disrupt navigational functions, or feed false information to operators. This can lead to incorrect positioning, course deviations, or interference with route planning and collision avoidance systems. In some cases, hackers could manipulate GPS logs or disable alerts, making detection difficult for navigational watchkeepers.
Often carried out remotely, hackers will look for vulnerabilities in wireless or satellite communication links to penetrate ship systems. Consequences can be severe, especially in congested or sensitive maritime areas.
Recent cyber incidents have raised alarms. In 2019, the U.S. Maritime Administration issued warnings after multiple vessels in the Strait of Hormuz reported unusual GPS behaviour and suspected hacking. Hackers could exploit vulnerabilities in outdated or unprotected navigation systems, targeting a vessel’s GPS to mask illegal activities, reroute ships, or create false position reports.
Update Software and Firmware: Ensure all onboard systems are running the latest, security-patched versions.
Secure Network Access: Isolate navigation systems from external networks and limit remote access.
Implement Multi-Layered Navigation: Use independent systems such as radar, AIS, and inertial navigation for cross-checking positions.
Training in Cyber Awareness: Educate personnel both ashore and afloat to recognise signs of cyber intrusion or GPS anomalies.
The threat of GPS interference in the shipping industry necessitates urgent attention and action by all stakeholders. By enhancing awareness, adopting advanced technologies, and fostering international cooperation, the industry can better protect itself against the disruptions caused by jamming. As geopolitical tensions continue to influence maritime operations, proactive measures will be essential to ensure the safety and efficiency of global shipping routes.
With thanks to Windward AI for their assistance with this article.
