NKVD Order no. 00439 signed by Nikolai Yezhov on July 25, 1937 was the basis for the German operation of the NKVD in 1937-1938.

The operation was the first in the series of national operations of the NKVD.

The order commanded to arrest citizens of Germany, as well as former German citizens who assumed the Soviet citizenship. German citizens who worked at railways and defense enterprizes were qualified as "penetrated agents of the German General Staff and Gestapo", ready for diversion activity "during the war period" (!NB: the war was considered imminent).

During the first month of the operation 472 persons were arrested, the total number was around 800 persons, or about 20% of the whole number of registered German citizens.

The order also instructed to be prepared for the second wave of repressions, against Soviet citizens of German ethnicity. So in fact, the total number of Germans repressed during the Great Purge for various reasons was orders of magnitude larger.