Ironically, Sorge's spying for the Soviets in Japan in the late 1930s was probably safer for him than if he had been in Moscow. Claiming too many pressing responsibilities, he disobeyed Josef Stalin's orders to return to the Soviet Union in 1937 during the Great Purge, as he realised the risk of arrest because of his German citizenship. In fact, two of Sorge's earliest GRU handlers, Yan Karlovich Berzin and his successor, Artur Artuzov, were shot during the purges. In 1938, the German ambassador to Britain, Joachim von Ribbentrop was promoted to foreign minister, and to replace Ribbentrop, Dirksen was sent to London. Ribbentrop promoted Ott to be Dirksen's replacement. Ott, now aware that Sorge was sleeping with his wife, let his friend Sorge have "free run of the embassy night and day", as one German diplomat later recalled. Ott tolerated Sorge's affair with his wife on the grounds that Sorge was such a charismatic man that women always fell in love with him and so it was only natural that Sorge would sleep with his wife. Ott liked to call Sorge Richard der Unwiderstehliche ("Richard the Irresistible"), as his charm made him very attractive to women. Ott greatly valued Sorge as a source of information about the secretive world of Japanese politics, especially Japan's war with China, since Ott found that Sorge knew so many things about Japan that no other Westerner knew that he chose to overlook Sorge's affair with his wife.