Sorge was arrested shortly thereafter, on 18 October 1941, in Tokyo. The next day, a brief Japanese memo notified Ott that Sorge had been swiftly arrested "on suspicion of espionage", together with Max Clausen. Ott was both surprised and outraged as a result and assumed that it was a case of "Japanese espionage hysteria". He thought that Sorge had been discovered to have passed secret information on the Japan-American negotiations to the German embassy and also that the arrest could have been caused by anti-German elements within the Japanese government. Nonetheless, he immediately agreed with Japanese authorities to "investigate the incident fully". It was not until a few months later that Japanese authorities announced that Sorge had actually been indicted as a Soviet agent.