A drone strike is parallel to an airstrike, now, I am unfamiliar with any airstrikes EVER used on or in the continental US ever. For any reason. Using a drone for surveillance is acceptable by my lights, but armed, and used offensively to harm people on US soil, THAT is crossing a line. Perhaps, alternatively, there should be a rather exceptional example to justify such a thing.
I have mixed feelings about drones....they're effective without putting military personnel at risk, but I can't shake the feeling that they're sneaky and underhanded somehow. They could also so easily be misused.