Today I took the time to have a closer look. Turns out, the directional antenna for M-code is only present on Block III GPS satellites, and only four of those are currently in service:
So this is definitely not the correct explanation.
Besides, even if there were enough Block III satellites in orbit to provide constant cover of the affected area, it would still make little sense to tie up their most advanced capabilities to jam their own legacy signal, when you could just turn off the legacy signal when transiting the target area and provide your own military with continued service using the directional antenna.
And of course, Russia has its own satellite navigation system
https://en.wikipedia.org/wiki/GPS_Block_III
So this is definitely not the correct explanation.
Besides, even if there were enough Block III satellites in orbit to provide constant cover of the affected area, it would still make little sense to tie up their most advanced capabilities to jam their own legacy signal, when you could just turn off the legacy signal when transiting the target area and provide your own military with continued service using the directional antenna.
And of course, Russia has its own satellite navigation system
https://en.wikipedia.org/wiki/GLONASS
so you'd also have to explain what the US and NATO could hope to gain from turning off GPS.