Matters came to a head in 1937 when Hitler decided to help Joseph Stalin in the latter's purge of the Soviet military. Hitler ordered that the German Army staff should be kept in the dark about Stalin's intentions, for fear that they would warn their Soviet counterparts due to their long-standing relations. Accordingly, special SS teams, accompanied by burglary experts from the criminal police, broke into the secret files of the General Staff and the Abwehr and removed documents related to German-Soviet collaboration.