@hightor,
Technically and especially practically we, here in Germany, had a lot to do with the KGB:
- the GDR Ministry for State Security (MfS) was built up under the strict guidance of Soviet secret services (NKVD, MGB and KGB respectively) and worked closely with them until almost the end. Subordination to Soviet services was relaxed from 1957 onwards, but the KGB basically had the first and last word vis-à-vis the GDR comrades,
- the "Soviet Military Mission BAOR" (SMM BAOR, aka SOXMIS) was situated not far away from where I live. Personal there did have diplomatic immunity!, but they were also GRU (Soviet Military Intelligence) and/or KGB officers.