Civil war happened a bit later, but I guess it's blurry because it was also mixed up with the foreign invasion / punishments that came out of the Soviet withdrawal from the war and Brest-Litovsk. The allies were enraged by the withdrawal from the war, but of course also extremely interested in destroying the new Bolshevik regime. So right away after 1918 they were thrown into a conflict setting.

I'd have to defer to an actual historian here for the full details, but my understanding of the history is that the "whites" that the Bolsheviks fought in the civil war were funded and aided by foreign powers (Britain, etc.), and that that funding and intervention began the moment Brest-Litovsk was signed, but then later transitioned into the full civil war scenario.

Of course it all depends on how you draw definitional lines around civil war vs revolution, etc.