 Naval activity during the Winter War was low . The Baltic Sea began to freeze over by the end of December , which made the movement of warships very difficult ; by mid @-@ winter , only ice breakers and submarines could still move . The other reason for low naval activity was the nature of Soviet Navy forces in the area . The Baltic Fleet was a coastal defence force which did not have the training , logistical structure , or landing craft to undertake large @-@ scale operations . The Baltic Fleet possessed two battleships , one heavy cruiser , almost 20 destroyers , 50 motor torpedo boats , 52 submarines , and other miscellaneous vessels . The Soviets used naval bases in Paldiski , Tallinn and Liepāja for their operations . 
