Operation North Wind (Unternehmen Nordwind) was a joint German-Finnish naval operation in the Baltic Sea in 1941, in the course of World War II. The operation itself was a distracting manoeuvre so that another German force could occupy the Estonian islands of Hiiumaa and Saaremaa without the interference of the Soviet Red Fleet. The operation suffered a major setback when the Finnish coastal defence ship Ilmarinen ran into a minefield and sank. It is uncertain if the Soviets ever noticed the fleet as they never responded.