The planned coup was cancelled after the signing of the Munich Agreement in September 1938.[439] Many of the same people were involved in a coup planned for 1940, but again the participants changed their minds and backed down, partly because of the popularity of the regime after the early victories in the war.[440][441] Attempts to assassinate Hitler resumed in earnest in 1943, with Henning von Tresckow joining Oster's group and attempting to blow up Hitler's plane in 1943.