What Russia did is save Latvia from being liquidated entirely by the Nazis.
lol
Correction: you were meant to say British-French-Polish-German treaty of 30th September 1938, that provided "legal" grounds for the German, Polish, and Hungarian annexation of pieces of land of Czechoslovakia, preceded by the United Kingdom and France "informally" asking Czechoslovakia to cede its Sudetenland territory to Germany on 20th September, which was followed by Polish territorial demands brought on 21 September and Hungarian on 22th September.