His arrest and sentence in 1946 first showed publicly that the Soviet Union had obtained atomic secrets by espionage.
The role he was allocated by his Soviet masters was the seduction of women working in Western embassies with the aim of obtaining secrets.
The same techniques used to obtain military secrets could be turned to complex commercial technologies or strategies without too much difficulty.
By 1995, the Energy Department had determined that it was highly likely that China had illegally obtained W-88 secrets.
Its aim was to deceive the West and to obtain key political, military and technological secrets which he intended to share with the Soviet Union.
A spy is a person employed to obtain such secrets.
The note alleged that two soldiers had been tortured to obtain Russian military secrets but managed to escape, and that the third, Butayev, was murdered.
Obtaining and using secrets from other syndicates is a violation of the America's Cup rules.
That information was a strong indicator that the Chinese had obtained national secrets.
His success in obtaining Soviet secrets allegedly led the Soviets to send a false defector on an ultimately unsuccessful assassination mission.