On 9 April 1940 Norway was invaded by Nazi Germany, and a German occupation followed. On 25 September 1940, Mehle was named as director of verbal programs in Norwegian Broadcasting Corporation radio. As one of two program directors, the other being Edvard Sylou-Creutz, Mehle was considered as the successor of pre-war broadcasting director Olav Midttun, despite being a subordinate of commissary president Wilhelm Frimann Koren Christie.