Soviet–Estonian Mutual Assistance Treaty

The Soviet–Estonian Mutual Assistance Treaty (Estonian: Eesti Vabariigi ja NSV Liidu vaheline vastastikuse abistamise pakt, Russian: Пакт о взаимопомощи между СССР и Эстонией, romanized: Pakt o vzaimopomoshchi mezhdu SSSR i Estoniyey), also known as the Bases Treaty (Estonian: baaside leping) was a bilateral treaty between the Soviet Union and Estonia, signed in Moscow on 28 September 1939. The treaty obliged both parties to respect each other's sovereignty and independence, and allowed the Soviet government to establish military bases in Estonia. These bases facilitated the Soviet takeover of the country in June 1940.

It was signed by Estonian Minister of Foreign Affairs Karl Selter and Soviet Commissar of Foreign Affairs Vyacheslav Molotov. Ratifications were exchanged in Tallinn on 4 October 1939 and the treaty became effective on the same day. It was registered in League of Nations Treaty Series on 13 October 1939.