After Nazi Germany invaded Norway on 9 April 1940, and Vidkun Quisling's party Nasjonal Samling (NS) became the only legal party, Dysthe sided with the German occupiers. He intrigued in order to weaken NS, and had contacts in the "Reichskommissariat Norwegen". At the same time he was a member of NS, although he claimed the reason for his membership was to inform the Germans about party affairs. Among others, he contributed to the downfall of Wilhelm Frimann Koren Christie as president of the Norwegian Broadcasting Corporation (NRK). Christie was a Norwegian nationalist and Quisling supporter, and as Dysthe was a special supervisor in the NRK from September 1941 he reported Christie to the "Reichskommissariat", who fired him. NRK had earlier been scrutinized by police inspector Gard Holtskog; however he advised to keep Christie and to limit the German influence.