The disruption to GPS services started getting worse on Christmas day. Planes and ships moving around southern Sweden and Poland lost connectivity last December 25 as their radio signals were interfered with. Since then, the region around the Baltic Sea—including neighboring Germany, Finland, Estonia, Latvia, and Lithuania—has faced persistent attacks against GPS systems.

Tens of thousands of planes flying in the region have reported problems with their navigation systems in recent months amid widespread jamming attacks, which can make GPS inoperable. As the attacks have grown, Russia has increasingly been blamed, with open source researchers tracking the source to Russian regions such as Kaliningrad. In one instance, signals were disrupted for 47 hours continuously. On Monday, marking one of the most serious incidents yet, airline Finnair canceled its flights to Tartu, Estonia, for a month, after GPS interference forced two of its planes to abort landings at the airport and turn around.

The jamming in the Baltic region, which was first spotted in early 2022, is just the tip of the iceberg. In recent years, there has been a rapid uptick in attacks against GPS signals and wider satellite navigation systems, known as GNSS, including those of Europe, China, and Russia. The attacks can jam signals, essentially forcing them offline, or spoof the signals, making aircraft and ships appear at false locations on maps. Beyond the Batlics, war-zone areas around Ukraine and the Middle East have also seen sharp rises in GPS disruptions, including signal blocking meant to disrupt airborne attacks.

Now, governments and telecom and airline safety experts are increasingly sounding the alarm about the disruptions and the potential for major disasters. Foreign ministers in Estonia, Latvia, and Lithuania have all blamed Russia for GPS issues in the Baltics this week and said the threat should be taken seriously.

“It can not be ruled out that this jamming is a form of hybrid warfare with the aim of creating uncertainty and unrest,” Jimmie Adamsson, the chief of public affairs for the Swedish Navy, tells WIRED. “Of course, there are concerns, mostly for civilian shipping and aviation, that an accident will occur creating an environmental disaster. There is also a risk that ships and aircraft will stop traffic to this area and therefore global trade will be affected.”

“A growing threat situation must be expected in connection with GPS jamming,” Joe Wagner, a spokesperson from Germany’s Federal Office for Information Security tells WIRED, saying there are technical ways to reduce its impact. Officials in Finland also say they have also seen an increase in airline disruptions in and around the country. And a spokesperson for the International Telecommunication Union, a United Nations agency, tells WIRED that the number of jamming and spoofing incidents have “increased significantly” over the last four years and interfering with radio signals is prohibited under the ITU’s rules.

On the Upswing

Attacks against GPS, and the wider GNSS category, come in two forms. First, GPS jamming looks to overwhelm the radio signals that make up GPS and make the systems unusable. Second, spoofing attacks can replace the original signal with a new location—spoofed ships can, for example, appear on maps as if they’re at inland airports.

Both types of interference are up in frequency. The disruptions—at least at this stage—mostly impact planes flying at high altitudes and ships that can be in open water, not people’s individual phones or other systems that rely upon GPS.