Between pragmatism and idealism: relations between Dutch astronomers and their Soviet colleagues during the Cold WarDuring the Cold War, outstanding astronomical research was conducted in the Netherlands, as well as in the Soviet Union. As there was a considerable overlap in research themes, astronomers in both countries stood to benefit from an exchange of ideas. During the Cold War, however, Soviet scientists were forced to withdraw from several international scientific organisations; foreign visits were minimised, and publication in foreign languages was forbidden. Moreover, several Soviet astronomers made highly derogatory statements about Western science. Nevertheless, communication and co-operation between Dutch and Soviet astronomers did not come to a halt in this period. Dutch astronomers even undertook considerable efforts to enable some of their Soviet colleagues to come to the West. Their reasons to do so varied, but ‘pragmatic internationalism’ seems to have been the mainspring motive. The Leiden astronomer Jan Hendrik Oort was the most prominent example of this movement. In some cases however, idealism was also a motive to involve the Soviets. For the Utrecht astronomer Marcel Minnaert, for example, co-operation with Soviet astronomers was in accordance with his ideal of international science. Contrary to what might have been expected in the Cold War period, the Dutch government was remarkably absent in this matter and did not interfere in the relations between Dutch and Soviet astronomers. This was most probably due the fact that the government considered astronomy a rather harmless field in science.