How quickly would reserve fleets return to service?

Would NATO or the Soviet Union recommission reserve ships after war began?

Yes; both would recover whatever was usable, and longer war duration would make wider reactivation increasingly likely.

Stored ships would return at different rates. Crews, refits, ammunition, and machinery condition determine which hulls can fight and how quickly. Reserve mobilization therefore becomes a time-dependent source of ships and equipment rather than an instant second fleet. The Soviet Union begins with a larger pool from which to draw, so its advantage grows more relevant as the conflict lasts beyond the opening weeks.