Sweden maintained its policy of neutrality during World War II. When the war began on 1 September 1939, the fate of Sweden was unclear. But by a combination of its geopolitical location in the Scandinavian Peninsula, realpolitik maneuvering during an unpredictable course of events, and a dedicated military build-up after 1942, Sweden kept its official neutrality status throughout the war. At the outbreak of hostilities, Sweden had held a neutral stance in international relations for more than a century, since the end of the Napoleonic Wars in 1814 and the invasion of Norway.

Sweden, following its long-standing policy of neutrality since the Napoleonic Wars, remained neutral throughout World War I between 28 July 1914 and 11 November 1918. However, this neutrality was not maintained without difficulty and Sweden at various times sympathised with different parties in the conflict.