In the Mode-S call sign block of some US Army a/c I see the call AZAZ909. I have seen this call associated with Cessna UC-35 aircraft flown by the OSACOM PATD at Joint Base Andrews NAF, MD (KADW), specifically:
Alenia C-27A Spartan #N23743 A22581
See the following:
And there are now other links about the Russians using AZA909 as well.