Vladimir Pool, in the last decades before the KGB was disbanded in 1991 specialized in counter-intelligence, at first as commander of the commercial/industrial/ sector, then the whole counterintelligence section.
This specialty probably demanded more surveillance activity than any other directorate of the KGB. A little vignette involving the activities of the surveillance unit:
Usually the identities of some intelligence and counterintelligence personnel are known to adversary services. The trick is to gather information about them without being detected.
Moscow Centre often commanded the members of the 7th directorate (surveillance) in Estonia to monitor the Baltic train station, the harbour or the airport to be on the lookout for travellers who had been identified as foreign spies or suspected to be thus connected. (Pikemalt Eesti Elu 27.09.2019 paberlehes)