The peninsula has great strategical value, as modern artillery based there would be able to reach more than halfway across the Gulf of Finland. If the same power would also control the Estonian coast, on opposite side of the gulf, it would then be able to block naval access from Sankt Petersburg to the Baltic Sea. Sankt Petersburg in turn is one of very few ice free ports belonging to Russia. Porkkala is furthermore located only 30 kilometers from Helsinki, the Finnish capital, and a foreign power based there would be able to exert significant pressure on the Finnish government.
During the Cold War the Soviet Union secured the rights of lease to naval base at Porkkala, in accordance with the armistice agreement that ended the Continuation War, between Finland and the Soviets, in 1944. Despite the fact that the Soviet lease for Porkkala ran for 50 years it was terminated in 1956 and control was handed back to Finland. This might be attributed the process of Finlandization, but the de-stalinisation of the Soviet Union under Nikita Khrushchev, and the fact that Sweden had not opted to become a member of NATO, where also important contributing factors.
At present, Porkkala is one of the main naval bases of Finland.