In April 1938, Goerdeler visited London, where he advised the British government both to resist the Nazi claim to the Sudetenland area of Czechoslovakia and to declare that he wanted to see the area transferred to Germany as soon as possible. As Gerhard Weinberg observed, Goerdeler's contradictory statements left the British somewhat confused. In the spring of 1938, Goerdeler, in association with Hans von Dohnanyi, Colonel Hans Oster and Johannes Popitz, became involved in planning a "putsch" against the Nazi regime should the regime launch "Fall Grün", the codename for the invasion of Czechoslovakia. In June 1938, Beck often consulted with Goerdeler over the question of whether or not he should resign as Chief of the General Staff as a way of stopping "Fall Grün".