Theorising I've seen on this - though, I don't recall where - suggested targeting resonances with HAARP in a similar way to how a human singer can shatter a wineglass, by projecting the crystals frequency, causing it to oscillate itself to pieces.

That is high-watt transmission power may not be required. And further, it was suggested it's not done in isolation by HAARP but cooperatively with various transmitters also transmitting the same frequency at the same target - using standing waves.

It makes sense conceptually as an idea but I'm not sure there if there's any evidence of it?