 The Åland islands had been demilitarized since 1921, through a League of Nations decree, which outlawed any military personnel or material on the islands.After the end of the Winter War, the Soviet Union controlled both the Hanko Peninsula and Estonia and the Finnish leadership feared that the Soviets were planning a landing in the demilitarized area.The Finnish militarization plan was ready by April and they started to move troops towards the coast between Turku and Pori according to the plan.