Thanks to Range for tip on this story.
Der Spiegel reported Herman Simm was a longtime spy for the Soviet Union and later Russia. His work would have remained Eastern Bloc local if not for Estonia joining Nato in 2004. His deep cover position in the Estonian Defense Ministry gave him access to NATO and thereby US and other Western secrets. He allegedly passed the names of all known spies in Estonia back to Russia.
Herman did his job by living a lie, many lies. He had Russian handlers who worked him well and garnered a great deal of intel. The article implies his last handler may have been a turncoat and possibly defected to the US. Ahh, spies.