This book will tell you why, still making my way through it, fascinating reading.

https://www.thriftbooks.com/w/the-sword-and-the-shield-the-mitrokhin-archive-and-the-secret-history-of-the-kgb_christopher-m-andrew_vasili-mitrokhin/259844/item/5331878/?gclid=CjwKCAjwiJqWBhBdEiwAtESPaKjKfcLtgSxRT88oh5meJasrvJ6q5UyqmhGgpzhiCdUV_yyEvFftQBoCVeMQAvD_BwE#isbn=0465003109&idiq=5331878

Vasily Mithrokhin brought his notes, as it were, from the SVR archives, the successor to the KGB, to England when he defected right after the fall of the USSR.

At this point I suspect we are also having a lot of assets brought back online, as Russia prepares for war with the west.

And your understanding is not wrong.