Some bunch was doing FOIA requests on HAARP, that ionospheric "heater" that has the knickers of the tin foil hat crowd in a bunch, and that produced some document that listed what the Pentagon considered to be the military applications of the project.
Not any superweapon, mind control, weather control, etc, but it's nonetheless interesting, although pretty mundane compared to all the conspiracy theories about it.
1) Enhance or mess up communication systems, including some over the horizon radar stuff.
2) In ELF mode, may have use in detecting large underground facilities
3) Can make the ionosphere "glow" in IR, perhaps degrading IR sensing and targeting.
4) Some limited anti-satellite effects.