This is what the borders of the USSR looked like by 1939. By the way, the map is Soviet of the same time. Going to negotiations with the USSR, London and Paris from the very beginning pursued a policy, delayed negotiations, trying to provoke a conflict between the Soviet Union and Germany, and this was done despite the warning of the British military about the benefits of London's agreement with Russia, the failure of which, in their opinion, could push Moscow into an alliance with Germany.