The ressources required to shoot stuff that's in the stratosphere are on a whole other ballpark than what your average revolutionaries can do.

Industrial-strength laser is all you'd need...

Intercepting stratospheric balloons is child's play, possibly literally, compared to intercepting chunks of metal flying at 10km/s, which are the alternatives under discussion.

> I'd be a lot more worried about them being dropped from stratospheric balloons - maybe not so useful for full scale bunker busting but extremely cheap to make and almost indefensible against as a strategic strike system.

If you meant to speak from the point of view of a revolutionary (why?) and note that stratospheric balloons would be a cheaper way of killing revolutionaries than ICBMs or Rods from God, sure, I agree. There are a million ways to shoot fish in a barrel. Forgive me for assuming your point-of-view party was militarily capable.

The Soviet Union spent 40+ years, and many pilots' lives, trying to devise a means of destroying CIA balloons operating at 30km altitude. SAMs, AAMs, artillery and even ramming all mostly failed.

Eventually by the late 1980s they developed the Myasishchev M-17 balloon interceptor aircraft, with a dorsal cannon-turret and able to loiter for hours at 22km. Still not quite sufficient.

Now increase the balloon altitude to 50km and they should be safe against any opposing force with early-2000s levels of military capability.

60+ km straight up is a long way to shoot.

Even satellites can be shot down:

https://en.m.wikipedia.org/wiki/Anti-satellite_weapon