Not a single spy was ever discovered

 What Happened the Last Time a President Purged the Bureaucracy

The impact can linger not just for years but decades.

On Jan. 22, 1953, his first day as secretary of state, John Foster
Dulles addressed a group of diplomats at his department's still-new
headquarters in Washington's Foggy Bottom neighborhood. For years, the
State Department had come under fire from Republicans and conservative
activists as a haven for Communist spies and sympathizers -- and not
without reason, since one of its rising stars, Alger Hiss, had been
convicted of perjury in January 1950 for lying about giving secret
government documents to a Soviet spy.

https://www.politico.com/news/magazine/2025/02/06/government-workers-purge-1950s-communism-00202336