The Great Terror in the Soviet Union 1937–38 was to a high degree accomplished on ethnic grounds. Citizens of German, Finnish and Polish and other descent became victims for the ‘national operations’ of the NKVD. In 1926 approximately 2,500 Swedes were residing in the Soviet Union. In April 1937 an NKVD-directive declared ‘to detect and remove from the USSR all foreign nationals, who in one way or another were suspected of espionage.’ Paradoxically the authorities tried to purge the country from ‘dangerous elements,’ but in the totalitarian communist system, returning home was still nearly impossible. The Embassy of Sweden in Moscow initiated a rescue operation, never before professionally studied. Hundreds of Swedish citizens in various regions of the country contacted the embassy in order to escape the threats from the NKVD. Many of them were from Karelia. Many were rescued, but in many cases the efforts failed. This unknown event gives a new perspective of Swedish diplomatic operations before World War II. But it also contributes to the wider issue of Western rescue operations in the USSR. Our paper is focused on the rescue operations of Sweden. How were they carried out? How did the Soviet concept of nationality affect the identification and misidentification of Swedes and Finns by the NKVD? Did the Embassy of Sweden in Moscow try to define ‘Swedish connection’ as broadly as possible? How important were the emotional reaction for the diplomats? The empirical results of this study open up for theoretical discussion on the relevance of moral and humanistic contents, as well as the principle of legal state in international conflicts and zones of insecurity. The source material is based on the collection of the Foreign Office discovered by the authors in the National Archives of Sweden, which contains various materials regarding the Swedish rescue operation.