I am certainly no expert on this matter, but I’d like to think that the military GPS signals are specially encrypted and cannot be jammed.
The article you referred to had the NORK spoofing civilian GPS signals. Our military uses the civilian GPS signal plus a,IIRC, fourth signal that causes military GPS to be more accurate; i.e., to within one meter vice 10 meters for civilians.
It stands to reason that if GPS is so vitally important to our military, it is “hardened” so it can be used in time of war.
But, I have been wrong before!
Your info is not up to date. Many commercial GPSs are accurate in inches. As far as encryption goes it can only work if it can receive the signal from the satellites which is very weak at the close to earth antenna. Flood the antenna with a stronger signal and the GPS is useless. That takes power and frequency range. A F-18 Growler has enough power to jam radar(s) for miles around it. Military radar signals are orders of magnitude stronger than the GPS signal here on Earth. During the Iraq war the Iraqi’s tried to use Russian built jammers against GPS guided bombs. worked intermittently because the bombs antenna moved faster than the jammer could follow. Boats? Easy to isolate and track with a jammer of sufficient power.