The Russian military has a large number of jamming equipment
Russia has advanced capabilities to destroy global positioning systems. Russia has more than 250,000 cell towers equipped with wifi jammer to withstand US missile attacks. And according to media reports, Russian GPS has disrupted Moscow and Ukraine. Indeed, Russia boasted of its ability to "render aircraft carriers useless". The US director of the National Intelligence Service recently released a report saying Russia and other countries are focused on improving their ability to disrupt US satellite systems.
A GPS jammer spoofing attack occurred in the Black Sea last month that involved more than 20 ships. Obviously, this is large-scale and blatant. Nautical experts and maritime executives are at a loss.
The incident was initially made public due to the relatively harmless security warning from the U.S. Maritime Administration:
A marine disaster reportedly occurred in the Black Sea on June 22, 2017 at 7:10 a.m. GMT. The location is 44-15.7N, 037-32.9E. This incident has not been confirmed. According to reports, the incident was due to GPS interference. Please be careful when crossing this area.
But the backstory is more interesting and disturbing. On June 22, a ship reported to the U.S. Coast Guard Navigational Center:
Near the coast of Novorossiysk, Russia, GPS devices are intermittently unable to receive GPS signals due to jammers. Now the accuracy of HDOP 0.8 is shown within 100 meters, but the position shown is actually 25 nautical miles. GPS indicator ...
After confirming that there are no anomalies in GPS signals, space weather, or ongoing tests, the Coast Guard recommends that the captain have GPS accuracy within his range of 3 meters and check for software updates.
The RNT Foundation has received numerous anecdotal reports on maritime issues with AIS and GPS in Russian waters, although this is the first publicly available and fully documented document known to us.
For a few days the GPS was positioned inland (near Gelendyhik Airport), but the ship was actually drifting 25 nautical miles away.
From this, the navigator can conclude that it is "spoofing" or sending the wrong signal to be clear enough that the recipient is providing the wrong information, even if it is not very subtle. They pointed out that the receiver said its antenna was 39 meters underwater and that all GPS satellites used had the same signal strength with a word error rate (WER) of 97% (less than 10% under normal conditions).