For centuries, sailors relied on constellations to safely guide them across the trackless tides. In modern times, those constellations have been artificial — the integral network of GPS satellites that support entire fields of guided navigation.

But unlike sailors of antiquity, who interpreted the heavens to plot courses based on the relative position of stars, GPS signals can be spoofed. Not just “can be,” but “have been,” posing a problem for the entire apparatus of oceanic navigation.

“Above Us Only Stars: Exposing GPS Spoofing in Russia and Syria” is a report published by C4ADS in April 2019 that details the ways in which spoofing has disrupted maritime traffic to Russia’s benefit.

C4ADS looked at nearly 10,000 suspected instances of spoofing in 10 different places that affected more than 1,300 civilian navigation systems, and it found an interesting common factor: Not only were the GPS systems spoofed, but the new coordinates to which the systems were spoofed were all airports.

Why airports?

The answer is not so much naval security as it is personnel security. Most drones are hard-programmed to avoid airports. Fool the drone into thinking it’s near an airport, and the drone will stay away. GPS spoofing is the easiest way to do that, and while it can be overridden with modification, it’s a good baseline to reduce the number of ambient drones that security personnel must worry about.

“The report also drew a strong correlation between the movements of Russian President Vladimir Putin and the spoofing events,” wrote Dana Goward of the Resilient Navigation and Timing Foundation, who contributed analysis to the report. “This reinforces speculation among many that the impact on ships is merely a by-product of the Russian government trying to protect its VIPs from drones.”

For seafarers, the immediate workaround involves a regression to other navigation systems, and close monitoring of GPS navigation near coasts to avoid setting course for the wrong kind of port.