The time and location data provided by GNSS systems are widely used in navigation systems, and signal disruptions can cause unexpected failures in positioning and ship autopilot systems.

GNSS interference makes navigation more difficult for ships, increasing the risk of accidents, including serious environmental damage.

The disruptions have been traced back to Russia and Belarus, as they try and protect their critical and military infrastructure from drone attacks. Last week, Estonia was one of 13 EU member states to demand more action from the European Commission over the issue.

The number of disruptions in the Gulf of Finland has been steadily increasing during the first half of the year and intensified further in June, the Transport Administration said in a statement.

Due to the increased frequency of disruptions, Finland and Estonia have now issued a navigation warning for the Gulf of Finland, covering the territorial waters and exclusive economic zones of both countries.

"Since May 2024, Estonia has been continuously informing ships about the interference," said Olavi Heinlo, head of the agency's cartography department.

"The growing number of disruptions increased the need to share more information with ships, which is why we are working with our Finnish colleagues and have added a specific danger area to the electronic charts and updated the message in the Notices to Mariners," he added.

Heinlo said that issuing warnings about various hazards is part of the "routine daily work" of authorities in both countries.

Finland and Estonia are also reporting the disruptions to the International Maritime Organization, which distributes the information to all 176 of its member states.

The Gulf of Finland is a busy shipping lane and also has dozens of passenger ferries crossing back and forth each day between Estonia, Finland and Sweden.

The level of GPS interference over the region was "high" at over 10 percent on Sunday, the website gpsjam.org reported.

GPS and GNSS interference have caused problems with navigation of planes, ships, drones and other vehicles, such as tractors, in Estonia for almost two years. 

Estonian officials have said the interference does not pose a direct threat as procedures and equipment have been improved. But disruptions occur "daily" and "they originate from across the national border — namely the St. Petersburg region," said Erko Kulu, head of the Consumer Protection and Technical Regulatory Authority's (TTJA) frequency management division.

In the wider Baltic Sea region, interference around the heavily militarized Russian exclave Kaliningrad is often felt.

"Drone chaos"

Both Poland and Lithuania have reported GPS jamming affecting their airspace over the past week.

Drones along Lithuania's coast and in northern Poland have become uncontrollable or crashed due to blocked GPS signals.

"This may be Russia's answer to the Baltops exercises," Polish Vice Admiral Krzysztof Jaworski told Reuters on Tuesday, referring to NATO's annual exercise in the Baltic Sea, being held this month. 

GPS signal jamming has increased sevenfold, according to the Lithuanian Armed Forces. Drone pilots report the worst disruptions near the coast and the Curonian Lagoon, closest to Kaliningrad, LRT reported.  

Additionally, on Monday, a flight from Alicante in Spain to the northern Polish city of Bydgoszcz was redirected due to navigation problems, TVP World reported.

This article was updated to add information from Poland and Lithuania.

--

Follow ERR News on Facebook, Bluesky and X and never miss an update!