It was actually the French (and by extension the British) who showed little interest in honoring the Franco-Soviet alliance. The French had watered down the treaty during its inception (the mechanism for actual military action included taking the case to the League of Nations), but more importantly the French refused to coordinate military preparation with the Soviet Union. The Munich Agreement of late 1938 further distanced French and Soviet defense policy in two important ways. First, the French and the British did not include the Soviet Union in negotiations over the transfer of the Sudeten from Czechoslovakia to Germany (they did not include the Czechoslovaks either), indicating a clear unwillingness to work with the Soviet Union. Second, by reaching the deal with Hitler at Munich, the French undermined the system on which the Franco-Soviet alliance rested, since the Czechoslovaks also maintained treaties with both the French and the Soviets that were also aimed at containing German aggression. French acquiescence at Munich essentially negated the treaty with the Czechoslovaks, and, by extension, the Czechoslovak-Soviet treaty, since its language depended on a French military response.

After Munich and some months later the German occupation of all of Bohemia and Moravia, the Soviet Union continued to push for a concerted response to German aggression. In fact, all of Soviet policy over the last half decade had shifted towards such a stance (notably, where they had called for Communists around Europe to oppose the supposedly capitalist-aligned socialist parties prior to Hitler's rise to power, the Soviet Union had since called for Communists to work with all anti-Fascist elements to stop fascism's rise in Europe). Only after it became clear to Stalin that the French and British would not work with him did he turn towards forming a non-aggression treaty with Hitler.