There are a number of unwritten rules in the world of espionage. These practices of the profession — though quietly accepted universally as “fair game” — can engender haughty rhetorical denunciations when an offending state is caught engaging in them.
Sometimes, countries will strategically disclose evidence of these sorts of intelligence activities. But, much more frequently, these actions remain hidden to the public. Governments know it generally isn’t in their self-interest to draw attention to the workaday, business-as-usual world of intelligence. (Plus: What a rival spy service doesn't know that you know about their efforts can offer many counterintelligence advantages.)
For instance, it’s universally understood that a country's diplomatic facilities abroad themselves are going to be the object of attempted sustained technical spying or eavesdropping by the host state (and likely some third countries, too). It’s just the nature of the game.
Recently, I obtained a set of declassified 1980s intelligence files from Poland’s cold war-era archives. The files detailed a Soviet operation to identify and remove a cornucopia of bugs placed in Russian diplomatic facilities across the United States. The document — written in Russian and almost certainly produced by the KGB, unlike the other Polish-language files in the tranche of documents — provides a meticulous pictorial account of the ways in which the U.S. spy services sought to technically surveil the Russians on American soil. The file offers an unprecedented, stunning — if dated — look at these efforts to eavesdrop on Russian government activities within the U.S.