What we know so far: When senior maritime intelligence analyst Michelle Wiese Bockmann opened a live vessel-tracking map of the waters off Iran, the United Arab Emirates, and Qatar, she saw a sight that defied logic. Hundreds of commercial ships appeared bunched into near-perfect circles, some even hovering on land – an impossible scene in one of the world's busiest maritime corridors. The clusters were not a data glitch but the visible footprint of an invisible war: large-scale GPS interference sweeping across the Strait of Hormuz.
The interference has scrambled the Automatic Identification Systems (AIS) that ships rely on to share their positions. That means tankers carrying hundreds of thousands of tons of oil may not know exactly where nearby vessels are – a potentially catastrophic problem in narrow waterways, where even a small navigational error can trigger an environmental or security crisis.
"We can't over-estimate the huge danger this places to maritime navigation and safety," Bockmann, who tracks real-time anomalies at maritime AI company Windward, told the BBC.
GPS jamming works by overwhelming a satellite receiver with counterfeit or high-power signals, preventing it from locking onto genuine transmissions from orbiting satellites. Because legitimate Global Navigation Satellite System (GNSS) signals are faint – roughly equivalent to the power of a 20-watt light bulb spread across the entire Earth – even modest jamming equipment can blind location systems within several miles.
Electromagnetic interference of this kind is not new. It has become a daily feature of electronic warfare in Ukraine and was recently blamed for disruptions to aircraft navigation over Europe, including a plane carrying the President of the European Commission. But analysts say the current interference blanketing the Strait is unprecedented in both scale and precision. "This is next-level," Bockmann observes.
Neither Iran nor any foreign military has acknowledged responsibility, yet experts strongly suspect multiple actors. Iran has previously used jamming tools – likely sourced from Russia or China, or built domestically – to disrupt foreign vessels and drones. Western analysts also note that US forces in the region likely employ counter-jamming systems to shield bases and ships from GNSS-guided weapons, potentially creating a dense electromagnetic battlefield in which both offensive and defensive signals coexist.
Detecting jamming activity can be as complex as navigating through it. When the war in Ukraine intensified, US technologist Sean Gorman and his team at Zephr.xyz used smartphones attached to drones to measure GNSS interference. The devices collected satellite-signal strength data, making it possible to triangulate jammer locations on a map. Gorman says the data revealed where jammers were operating and the strength of their signals.
More recently, with Iranian airspace closed to civilian aircraft, Gorman used radar satellites to spot the same telltale distortions in radio frequencies. The interference appears as faint patterns in the radar returns – a kind of digital fingerprint left by the jamming devices themselves. These traces have revealed widespread disruptions around Iran and the wider Gulf.
Maritime safety agencies, including Pakistan's National Hydrographic Office, have already issued warnings about the interference. A collision in these waters could have global economic consequences, given that roughly one-fifth of the world's crude oil passes through the Strait of Hormuz.
Defense contractors and navigation firms are now racing to build tools that can operate in jamming-heavy zones. Raytheon UK's "Landshield," a puck-sized anti-jam antenna system, uses multiple channels to maintain stable positioning even under attack. "We're seeing quite an increase in demand and capacity for our anti-jamming products at the moment," said Alex Rose-Parfitt, the company's engineering director.
Other firms are developing GPS-independent navigation systems. Australia's Advanced Navigation uses gyroscopes and accelerometers – similar to those found in smartphones – to compute a vehicle's position relative to its last known coordinates.
The system can also cross-check optical imagery with satellite maps or even calculate location using star patterns, a modern nod to ancient celestial navigation. "Doing something like star-mapping is very inexpensive," says co-founder Chris Shaw. "It's just not very accurate. That's why you need multiple forms of location and position analysis."
The vulnerability of GPS lies in its openness. Civilian GPS operates on unencrypted signals that are easily mimicked or overpowered, while military systems use M-Code, an encrypted, authenticated form far more resistant to intrusion. Experts believe that the civilian navigation landscape will soon undergo the same kind of evolution Wi-Fi networks experienced, shifting from open and unsecured to tightly protected.
Ramsey Faragher of the Royal Institute of Navigation argues that the Gulf disruptions mark a larger turning point for global navigation. "Soon, we will look back on this era where we are using open GNSS signals and think, 'God, we were mad, that was really not a smart move,'" he says.
Image credit: BBC
GPS is getting jammed in the Strait of Hormuz, and ships are appearing in circles
