Why can living former spies divulge that they worked for spy agencies?

Governments may loathe details of the past to go public, as in the case of Alexander Litvinenko and Sergei and Yulia Skripal. Classified files can remain classified for many years. While former spies may be canny enough not to unveil or elaborate their former work, why isn’t (the fact of) their employment by agencies alone kept confidential? Can’t enemies still exploit former employees? E.g. enemies can blackmail them especially if they get indebted, or clandestinely kidnap them to the enemy state and coerce them to divulge everything they know. I’ll cite some prominent examples of former spies.

  • Ian Fleming.
  • John le Carré who worked for MI5 and MI6.
  • Jonna Mendez, former chief of disguise in the Central Intelligence Agency’s (CIA) Office of Technical Service. WIRED features her in YouTube videos.
  • Sandra Grimes – Wikipedia

The Central Intelligence Agency team that discovered Soviet mole Aldrich Ames. From left to right: Sandy Grimes, Paul Redmond, Jeanne Vertefeuille, Diana Worthen, Dan Payne.

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  • Ex-CIA Officer Reveals How Eateries Are Key To Spycraft : The Salt : NPR

“Restaurants and cafés are in many ways the lifeblood of espionage,” is how Amaryllis Fox puts it. Fox was a real spy. Her memoir, Life Undercover: Coming of Age in the CIA, released this month, recounts her adventures as a clandestine CIA operative from 2003 to 2010 deployed to 16 countries to infiltrate terrorist networks in the post-Sept. 11 world.