However, as a ballistic superiority position for planetary conflicts, space is the ultimate eagle eye. and dropping a mass large enough to survive reentry would contain more energy than an atomic blast (potentially.,
in Sci-fi novel
Footfall (by Niven and Pournelle in the 80s) an alien species arrives and succeeds in decimating all threats and transports planet-side nearly instantly just by dropping spikes at transport intersections, crippling the planet infrastructure.
Oh. I know, I just quoted Sci-fi as my main backup... so there are inherently a great number of issues with it, however, the ideas still hold, gaining higher ground has typically always provided the upper hand in conflicts.
Are the costs worth the "security" or strategic advantage... Not worth putting brianpower to today.
All that being said... I'm hoping we can use some of the ideas to inspire more remote control Aircraft...