The Geek Behind Google's Map Quest

I did a double-take reading this:

  Google Maps appears differently depending on the country 
  of your IP address, allowing the company to stay on the
  right side of the law in the many jurisdictions where it
  operates. Log in from China, for instance, and Google Maps
  is strictly controlled by the government, which
  deliberately inserts errors into GPS systems close to
  sensitive locations.

I already knew Google Maps will be rendered differently based on your location (http://qz.com/224821/see-how-borders-change-on-google-maps-d...) but this sentence is ambiguous - is Google inserting the errors? How do you insert errors into GPS systems anyway?

Guessing this meant that the Chinese government's GPS systems send your device incorrect lat/long coordinates near certain locations, but that seems counter-productive - wouldn't that just tip off people they were near a sensitive location?