So their _own_ GPS-system Glonass, not the US GPS.
When I was at the military we "learned" that encrypted communication makes no sense when the transmitted content effects events no longer than half a day into the future as the opponent cannot take effective countermeasures anyway.
>> The intelligence arm of the Ukrainian defence ministry said Maj Gen Vitaly Gerasimov, chief of staff of the 41st Army, had been killed outside the eastern Ukrainian city of Kharkiv, along with other senior officers.
https://www.independent.co.uk/news/world/europe/andrei-sukho...
>> Andrei Sukhovetsky was the commanding general of the Russian 7th Airborne Division and a deputy commander of the 41st Combined Arms Army, and by far the most senior Russian figure to have died in the conflict so far.
>> Mr Putin confirmed that a general had been killed in a speech updating the Russian people on the progress of the conflict, eight days into the deadly invasion.
This appears to be something like 75% of their total operational power, with obvious, serious problems, like relying on civilian GPS, being evidently wholly unprepared for the mud, the fact that there's no comms chain back so they rely on Ukrainian comms networks staying up, the lack of a supply chain, the fact that the domestic population is finally catching on to the fact that Putin is illegally using his conscripts on the front line, the consequent astonishing rate of desertion from an army who weren't told they were invading until they crossed the border to "keep peace", the death of two generals, more aircraft losses than they expected, etc.
It's quite a big fraction of their power and what is very striking is that they appear unable to fully support it
The only people really surprised by this attack appear to be essentially all ranks of the Russian army -- an army spoiled by corruption and grift.
The bigger question is which ends first? The war, or Putin?