Vessels transmitting AIS data over VHF (location, speed, bearing, name, size and rate of turn of vessel etc) help other ships from colliding with it - but it can't really be relied on for tracking and I'd be amazed if any military relied on it (In a military manoeuvre I'd guess they turn it off)
Presumably the GPS was blocked/misdirected 'by some means' and this got published by the AIS systems.
Presumably the GPS was blocked/misdirected 'by some means' and this got published by the AIS systems.