> The military has some additional protections

Feel this is somewhat an understatement, it's cryptographically signed and encrypted, as far as protection goes it's wandering onto an active battlefield naked vs being in a modern tank.

The newer satellites, of which 5 are in orbit, also have a directional antenna with which they will be able to boost the signal strength 20 dB (100 * power), using a new military M-code that no longer needs the other signals to lock on. The signal is sent both over the wide area and the spot beam antenna. Older satellites will only sent it over a wide area antenna. As far as I understand, this is not operational yet, but is planned for this year.

It is, but the US basically can't use that mode anymore - the widespread use of GPS guided munitions which do not have the military grade receivers means the US basically doesn't enable the signal degradation mode ever - it harms their own force more then helping any counter-force.

You're talking about SA (Selective Availability) but I think the parent comment is referring to the "fine" signal: https://en.wikipedia.org/wiki/GPS_signals#Precision_code

Or more likely the M-code which is the upgraded version of the P(Y) code.

Why do you assume munitions don’t have the “military grade receivers”?

Yeah, but that’s all worthless now. The US has lost the number of GPS satellites in the sky. It’s all Russian and EU sats now.

GPS jammers are also used by truckers, rental car drivers, etc., and they have stopped airplanes before:

https://www.cnet.com/culture/truck-driver-has-gps-jammer-acc...

It's also something air defense teams would use to try to redirect missles (make them miss their mark because they have to rely on less effective navigation matters)

On the other hand, radio transmission is relatively easy to locate, and ham radio operators do it for fun ( https://en.wikipedia.org/wiki/Transmitter_hunting ) ... so it should't be that hard to find a source.

What's more interesting is the deployment of certain radio jammers at airports [1] to dissuade drone operators from flying their toy into restricted airspace.

[1] https://www.forbes.com/sites/meriameberboucha/2019/01/28/how...

Also, do they also use Gallileo, Glonass..? is the Chinese GPS up yet ?