Potential counterargument: Second-strike capabilities are still relevant in the interstellar setting. You could build a bunch of hidden ships in the oort cloud to ram the foe and do equal devastation if the other party does it first, deterring a first strike even with tensions and an absence of communication. Further, while the “ram with high-relativistic objects” idea works pretty well for preemptively ending a civilization confined to a handful of planets, AI’s would be able to colonize a bunch of little asteroids and KBO’s and comets in the oort cloud, and the higher level of dispersal would lead to preemptive total elimination being less viable.
Potential counterargument: Second-strike capabilities are still relevant in the interstellar setting. You could build a bunch of hidden ships in the oort cloud to ram the foe and do equal devastation if the other party does it first, deterring a first strike even with tensions and an absence of communication. Further, while the “ram with high-relativistic objects” idea works pretty well for preemptively ending a civilization confined to a handful of planets, AI’s would be able to colonize a bunch of little asteroids and KBO’s and comets in the oort cloud, and the higher level of dispersal would lead to preemptive total elimination being less viable.
That’s possible, but I’m guessing that it’s not hard for a superintelligent AI to suddenly swallow an entire system using something like gray goo.