Central Intelligence Agency (CIA http://www.cia.gov/) reports relating to Amateur Radio in the former Soviet Union (including the Baltic States) and Warsaw Pact countries are among documents declassified to a new searchable online database: https://tinyurl.com/CIA-HamRadio , the CIA Freedom of Information Act (FOIA) Electronic Reading Room.
Documents cover translations and assessments of Amateur Radio clubs; training; monitoring Sputniks; technology and equipment; QSL cards, and ruminations on a plan to monitor US ham radio transmissions for activities "of interest" to the intelligence community. Searches on "Amateur Radio" or "ham radio" will yield multiple documents, some heavily redacted.
For example, a 1949 memo largely dismissed the use of Amateur Radio in the Soviet Bloc as an intelligence-gathering tool. "Except for possibilities in the counter-espionage field, it is believed that exploitation of amateurs with reference to the USSR and satellites could lead at best only to information concerning the location of ham transmitters, an item of dubious intelligence value," said the memo, which carried the subject line "Exploitation of Radio Amateurs."
Another memo from the same year showed that the USSR viewed the growing "cadre" of radio amateurs as the next generation of engineers. Documents covering a wide range of topics not necessarily related to Amateur Radio also have been declassified, sanitized, and made available to the public for the first time in this archive.
Some of these documents were only available previously in a closed system at the US National Archives https://www.archives.gov/.