On 22 June 2017, the US Maritime Administration filed a seemingly bland incident report. The master of a ship off the Russian port of Novorossiysk [Black Sea] had discovered his GPS put him in the wrong spot – more than 32 kilometres inland, at Gelendzhik Airport.
After checking the navigation equipment was working properly, the captain contacted other nearby ships. Their AIS traces – signals from the automatic identification system used to track vessels – placed them all at the same airport. At least 20 ships were affected.
https:// maritime-executive.com/editorials/mass-gps-spoofing-attack-in-black-sea#gs.1h0gwpU
Belka Car, a car sharing service in Moscow, also warned its customers that GPS signals in Moscow were "unstable" and could misidentify the car's location as being in Romania.
So the Russians got it sea-worthy.