中苏关系
During his years as a field agent, Karla traveled in several countries, recruiting agents who would later become highly placed in their respective national regimes. He traveled to England in 1936 and 1941 and recruited Bill Haydon, code-named "Gerald", who eventually became the number-two man in the "Circus" (the British Secret Intelligence Service). At another time he recruited Nelson Ko, a high-ranking technocrat in the People's Republic of China (according to Connie Sachs, Karla was one of the few Soviets to predict the souring of Sino-Soviet relations).