I say let him send the doctors and watch half of the defect.
You guys underestimate Castro's treachery. Ponder it a while. If I wanted to ensure there were outbreaks of cholera, typhoid, yellow fever and malaria, I wouldn't use soldiers. I'd use doctors.
Also, it's a fair bet that none of those doctors are leaving Cuba without first being made painfully aware that their families will suffer horrible fates if they defect.
C'mon guys...this is Communist Thuggery 101!