Keller, Jakob Schaffner and Ernst Hofmann, as representatives of the NBS, received an audience with the Swiss President Marcel Pilet-Golaz (in office throughout 1940) in which they demanded much closer relations with Nazi Germany, leading to eventual incorporation.[2] This was followed by a Munich conference in October 1940 to which the Director of the Reich Security Main Office, Reinhard Heydrich and the Swiss doctor and SS-member Franz Riedweg invited the leaders of the NBS and of other Swiss groups in order to increase cohesion.[2] Ultimately the meeting strengthened the hand of the NBS, as the remnants of the Bund Treuer Eidgenossen Nationalsozialistischer Weltanschauung as well as the Eidgenössische Soziale Arbeiter-Partei and Ernst Leonhardt's Nationalsozialistische Schweizerische Arbeitspartei agreed to be absorbed into the movement.[2]
Despite this strengthening the National Movement did not last long, as the Swiss Federal Council feared that annexation by Germany was just around the corner.[2] In a series of moves against the most extreme groups, the NBS was closed down on 19 November 1940, by which time it had 160 cells and around 4,000 members.[2] The group continued to work underground for a time before a police crackdown which led to most of the leadership fleeing to Germany.[2] Whilst in Germany Keller set up the Bund der Schweizer Nationalsozialisten as an émigré movement, although its influence remained limited; eventually he returned to Switzerland in 1941.[2] Meanwhile, various NBS units continued underground activity secretly, mostly with help from the SS, until World War II ended in 1945.[2]