I recently listened to the 80k podcast summary of Space Warfare Seems Mostly Defense Dominant. After reading and sharing it someone linked me the seemingly conflicting Colder Wars that argues space combat favours the attacker. My thoughts on the matter have also leaned towards thinking of warfare in space as offence favouring. It now seems to me that it is more of a spectrum primarily based on the distance of the adversaries to one another.

If adversaries are roughly equally resourced then a first strike carries more advantage with less distance between them, while with more distance the defender has more time to react to subluminal attacks, and more opportunity to randomize their positioning against luminal attacks, decreasing the attacker's ability to target the defender's position effectively.

How would this model play out with more asymmetrically resourced adversaries?

Clearly, with large distances, a less resourced attacker doesn't stand a chance of damaging the more resourced defender.

The main strategy I see for a more resourced distant attacker would be to overwhelm the defender's capacity to respond to attacks by targeting a much larger volume of effect with their luminal weapons, or sending large enough swarms of subluminal weapons so that the defender is unable to respond to all of them. A defender with distant adversaries needs to keep the cost of a successful attack high enough that their potential attackers are not willing to sink their resources into the attack.

The key question for defenders is then figuring out how much energy is required to defend against their potential adversary at the minimal expected distance. If they meet this defence budget then they should be safe from similarly sized adversaries at greater distances, and somewhat larger adversaries at these distances and longer too.

If an attacker is very patient, they could send Von-Neumann probes to galaxies that are on a collision course with their adversary and wait for the distance to close and then begin their first strike. If the defender can detect the launch and trajectory of the probes then this could precipitate conflict in these collision bound galaxies. This would seem to imply that a defender should preemptively claim the galaxies that are on a collision course with them.

How would strategies change with different and more complex adversarial layouts? For example, two adversaries that occupy the same galaxy, but the territory they control is highly intertwined and nebulous ^[1] , so most controlled spatial volumes are both very close and very far from the spatial volumes controlled by their adversary. Or, the opposite case, where the adversaries have split a galaxy in half and have one very clearly defined border between their controlled spatial volumes. What are other interesting arrangements of adversaries, and what effects do the arrangements have on strategic stability?

1. This state could be caused by a galactic collision with a galaxy that has been successfully, and perhaps stealthfully, seeded. ↩︎