There was a discussion the other week of what war in space will look like, and I have a number of follow-on thoughts to it. This is one of them; others are probably forthcoming.
The general consensus was that if you can achieve orbital superiority over a planet, you've won. You can bombard its population centers into glowing rubble with kinetic weapons, and there's jackall the defenders can do about it. I voiced a minority opinion then, that the aim of one's campaign may preclude urban centers as bombardment targets, and that in order to conquer a population center one must necessarily have boots (filled with either flesh or sentient metal) on the ground for the messy work. I'm also not entirely sure about the current state of antisatellite weapons, but I expect that at the very least you could fill the most likely orbits with shrapnel as an area denial weapon.
Further reading on my part has reinforced this suspicion. I believe the predictions of Giulio Douhet are instructive. Douhet was an Italian officer in the early 20th century and one of the fathers of Air Power Theory. During the first World War, he advocated the construction of heavy bombers, which he believed could be used to bomb enemy population centers and cause the populace to revolt against their government. He also pioneered the notion later summarized as "the bomber will always get through." Douhet died in 1930, too early to see his theories tested during the second World War.
They did not stand this test well. Extensive conventional bombing of civilian population centers was undertaken against Britain and Germany, and Tokyo was also bombed (with amusing preparations underway for further bombing). Civilian morale did not crumble in any of these instances; in Britain "the blitz" as it was called strengthened civilian resolve, while the Germans kept fighting all the way to Berlin despite an absurd volume of bombs being dropped on them.
I think Douhet's theories about civilian morale were therefore misinformed. The last half-century of guerilla warfare seems to agree that Douhet was mistaken. As I mentioned in my previous short review of Fry the Brain, the essential method used by effective urban guerilla insurgencies is to incite security forces to inflict collateral damage on civilians, and thereby win the relatives of the injured to the insurgency's cause. Indiscriminate bombing strengthens the morale of the enemy. It lets mothers die in the arms of their sons, and there seems to me no surer way to make a devoted foe. If you want to win by sapping civilian morale, you should instead strive to kill many sons in a distant land while leaving their mothers alive to lament over them. Total war in practice relies on destroying the enemy's ability to fight, to resupply and reinforce (for which civilians are necessary), rather than his will to fight. Infrastructure targets are still on the table, though, and pinpoint kinetic strikes against them do seem liable to reduce the enemy's ability to retaliate, but then you have the post-conquest problem of rebuilding all the dams and bridges you just blew up to make the conquered planet useful again. So it seems to me that fixed military targets - command centers, missile silos, strategic fuel reserves, airfields, space launch sites - are probably the most promising for orbital bombardment.
Anyway, to return to Douhet - by the 1960s, "the bomber will always get through" had fallen by the wayside. A British study in 1964 concluded that a strategic bomber inbound to the Soviet Union would meet on average six SAM/AAMs, each with a 75% probability of destroying it if countermeasures were not employed.
I think Douhet's case is much analogous to our own. We see a novel means of offense, possible today but not yet deployed, and we cannot conceive of an effective/cost-effective counter to it. We therefore are inclined to think that it will be an end-all-be-all of warfare to achieve orbital superiority over an enemy world, much as Douhet thought of air superiority. But there is a concept in Filipino martial arts called tapi tapi; it means broadly "counter for counter". There's always a counter, and for that counter a counter, and so forth. We maybe haven't found the best counter to orbital bombardment yet, but I think we will. Maybe we can't bury our command centers beneath any reasonable amount of concrete in the face of tungsten rods at Mach 10... but such weapons are also fairly lousy for hitting moving targets. Perhaps a widely distributed, redundant mobile command center is the answer (to the cloud!... half-sarcastic, but half-serious). If, as it is said, "fixed fortifications are monuments to man's stupidity", perhaps fixed installations and formations are as well. Welcome to the digital age! Granted, you're not going to be able to get unenhanced humans to move continuously at such a pace in peacetime... but that's what machines are for. If your enemy has a big hammer, become as a swarm of flies; present too many targets, each of which is waaay overkill for a 12 kiloton kinetic weapon if you can even hit it with one. And keep them in or near population centers, so you get some collateral damage morale out of them...
(As for the computer security implications of a cloud command center... well, some might call that job security d: )