That would be a disaster if true.
But a foreseeable one. Seeing that it's obvious to me, with no military experience, just an old hex-grid wargamer's grasp of things tactical and strategic, that the US military's reliance on GPS is an an Achilles heel waiting to be attacked, it surely is clear to professional military men on both sides of all possible conflicts.
At least I hope it is to our side. Question to anyone in the military now: do soldiers and low-level officers still get access to and the training to use paper maps in tactical and operational situations? I ask that because it's probably the one non-classified indication of preparation for a no-GPS or corrupted-GPS combat environment. (Technical fixes for precision munitions that default to use GPS would surely be classified if they exist.)