They are doing this in bigger Russian cities. GPSes often doesn't work in downtown Moscow or St. Petersburg. There's plenty of information available on the internet about this. Also, they have their own positioning system, that is also available worldwide - Glonass

Care to link to any of that information?

Stuff like: https://themoscowtimes.com/articles/the-kremlin-eats-gps-for... http://money.cnn.com/2016/12/02/technology/kremlin-gps-signa...

Could just as well be the US. When selective availability was disabled they said they will come up with something new to deny hostile forces accurate GPS. [0]

> Develop measures to prevent the hostile use of GPS and its augmentations to ensure that the United States retains a military advantage without unduly disrupting or degrading civilian uses.

GPS only being jammed at higher altitudes, but not on the ground fits the above pretty well imo. We don't know how this jamming would affect US military GPS usage, but it's not impossible to think that it doesn't.

[0] https://www.faa.gov/about/office_org/headquarters_offices/at...

It's bad if you relly on one and only system. As there is NAVSTAR GPS, Glonass and Galileo you'll have to jam your own system too.

All current aviation GNSS systems only use GPS (US system) as far as I'm aware. There are some GLONASS dongles such as Garmin GLO, but they're not IFR approved.

GPS and Galileo use the same frequency for their public service. Jamming one gets them both.

Glonass is a couple hundred megaherz away from GPS L1.

So there is no reason NOT to support Glonass.

Except the Russians run and control it and may consider opportunities to weaponize it offensively against unsuspecting Western users.

The best bet is to use as many positing systems as possible in order to prevent attacks narrowly targeting one positioning system.

The same can be said to NAVSTAR GPS. The only system which is not primarly built for military uses is Galileo.

Yes, that's what I am saying. Don't rely on one system. Using more also increases accuracy.