On Fri, 15 Nov 2019 18:58:30 -0800 (PST), Its Me
wrote:

What it sounded like in the article is that the AIS systems in the ships were being spoofed to report false
locations. If the entire GPS system was being spoofed ALL the locations would be jumping around.

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The AIS transponders get their positions from GPS. It's not necessary
to jam the entire GPS system, just over ride the locally received
positions with a stronger signal. That is fairly easy to do since GPS
receiver antennas are omni directional.