Originally Posted By: Hpasp

As far as I know, generally they jammed the missile Beacon signal (Downlink).
I know only that the A-12/SR-71 was trying to inject false missile guidance commands (Uplink), but it was a futile attempt.

True... About SR-71 - it has (since 1972 I think) a possibility to "interrogate" SA-2 missiles and thus find which launch is fake or real.