In my stamp collection is a 1990 Soviet Union stamp commemorating British double agent Kim Philby. Above his likeness is the title СОВЕТСКИЙ РАЗВЕДЧИК, which to my understanding translates to "Soviet Sentry". The term "sentry" strikes me as odd though, because sentry isn't a synonym for spy. Can somebody shed any light on this particular choice of wording?
An online dictionary indicates the term means "sentry" which doesn't make any sense. Kim Philby was a British double agent, not a "scout", but obviously the USSR considered him valuable, and perhaps a hero. So does the particular Russian term have a more nuanced meaning when it comes to espionage, or does it perhaps mean "Guardian of the Soviet Union", or something else entirely?