GPS systems in Moscow air space

Pilots of civilian aircraft have reported incidents of failure of the GPS system in Moscow air space on Wednesday evening, two sources from the air traffic control service told ITAR-TASS.
One of them reported mass incidents of failure of the GPS system on board aircraft with reference to reports from at least twelve air crews.
The other source told ITAR-TASS that late on Wednesday around ten air crews reported incidents of failure of the GPS system, which was off for 5 -10 minutes, at the altitude from 9,000 to 10,000 meters.
No explanations of the causes of the failure of the navigation system are available yet.