Presumably the solution should be to shoot down the HARM itself, if possible. Russia has recently deployed the S-350 to Crimea, possibly in response to the recent strikes, as their first sighting occurred ~1 week after the incident at Novofedorovka, and they showed up at Gvardeyskoe. Sources speculate that this is a new unit of S-350s re-arming the 1096th Rgt from Osa to S-350 (quite the upgrade), but it's also possible this is the 1721st Air Defense Rgt out of Sochi, sent to Crimea.Yes of course. Even without proper integration, a HARM can dramatically increase success rates in certain scenarios.
First, HARM in its D variant which is confirmed to be used by Ukraine, has GPS guidance, so it's already better than any unguided long range rocket, and its 150km range (albeit at altitude and speed) gives it a farther reach than HIMARS.
We know HARM has multiple employment modes, of which one permits somewhat effective use even without digital integration with the aircraft.
Its ability to lock onto not only radars but also jammers allows it to hit with high probability targets that moved after aircraft lifted off.
It does however still suffer from ineffectiveness if the Russians simply switch off radars and jammers for a while.
This means HARMs might be somewhat useful for destroying Russian radars, but more useful for sneaking Ukrainian aircraft and other munitions past air defense bubbles.
I wouldn't be surprised if HARMs were instrumental in the recent Crimea strikes, when everyone was wondering "what the air defense doing?"