According to Gamepedia's Covert Ops Article, the Recruit Defectors Covert Ops mission will:
Gives the player a set of random military units at their capital.
I've attempted this Covert Op several times, but I haven't yet succeeded. What I'm curious about is how much damage some covert ops actually cause on the victim nation. It seems like there are always credits to siphon ("Despite the name of the operation, the defender does not lose any"). So I wonder does Recruit Defectors actually take an enemy unit from the target nation or does nothing negative happen to the victims?
Does the 'Recruit Defectors" covert Op actually remove units from the victim nation? or does it only produce new units?
If the victim doesn't lose units, does the victim civ suffer any negative effects?