One, they’re worried about how China and Iran could use Russian technology to beef up their military capabilities, and threaten their — or their allies’ — defence assets around the world.
Well duh.
Two, there’s deep concern about what such steps say about the Kremlin’s frame of mind. Russia had in the past heavily guarded its military advances, especially from potential future rivals such as China. Trading its knowledge now is seen by some as sign of increased recklessness.
Recklessness? To increase the military capabilities of the enemies of the world’s most reckless superpower?