'Stella Polaris' was a Finnish operation to move signals intelligence records, equipment and personnel into Sweden after the end of the 'Jatkosota' continuation war with the USSR (September 1944).

At this time the threat of a Soviet occupation of Finland was deemed probable, and the undertaking was conceived to provide a means of supporting guerrilla warfare in Finland in the event of any such occupation. The operation was undertaken by a team under the command of Everstiluutnantti Reino Hallamaa, and the records later fell into US hands.

The operation was based in the small fishing village of Nämpnäs in the Närpes area of Ostrobothnia, whence the archive was shipped to Swedish ports.

On 22 September a very substantial portion of the Finnish signals intelligence archive and capability was moved to Sweden with the active support of Major Carl Peterson, the director of the Swedish Försvarsstabens intelligence apparatus. About 750 personnel people were transported through Finland for movement, together with crates of archives and signals equipment, across the Gulf of Bothnia in three ships from Närpes and Harnosand and one ship from Uusikaupunki and Gävle.

After the Moscow armistice agreement had left most of Finland in Finnish hands, late in 1944 and early in 1945 the majority of the Finnish staff with families returned home, the exception being those hired by the FRA (Swedish national defence radio establishment. To help ensure that the entire programme remained secret, those returning to Finland did so in small groups which crossed frontier along the Torne river.

Sweden offered to take over the equipment and some of the documentation, and the FRA thus gained invaluable access to technical equipment and seven crates of archives, and these became an important foundation for the newly established FRA’s activities. In an undertaking codenamed 'Ledaren', the Swedes later sold microfilmed material to Japan, the USA and other countries.

'Stella Polaris' provided a quick start to Sweden’s post-war intelligence capability through access to a huge amount of dedicated material and signal technologies, while for Finland the operation resulted in the removal, in some cases to prison, of several communist and pro-Soviet elements in the Finnish political establishment.