The Eastern Pact was a proposed mutual-aid treaty, intended to bring France, the Soviet Union, Czechoslovakia, Poland, Finland, Estonia, Latvia, and Lithuania together in opposition to Nazi Germany.
The idea of the Eastern Pact was advanced early in 1934 by the French minister of foreign affairs, Louis Barthou, and was actively supported by the Soviet government.
In May and June 1934, the Soviet Union and France agreed to conclude a bilateral treaty providing for France's guaranteeing of the Eastern Pact and the guaranteeing of the Locarno Treaties of 1925 by the Soviet Union.
On 14 June 1934 the Soviet government invited all interested states to participate in the Eastern Pact.
Barthou appealed to the British government in the name of the French government, but the British, while formally approving the idea of the Eastern Pact, made their support conditional on Germany's inclusion both in the regional mutual-aid treaty and in the Franco-Soviet Treaty so that Soviet and French guarantees would be extended to Germany.