Border states (Eastern Europe)

During the interwar period, the nations of Western Europe implemented a border states policy,[1] which aimed at uniting them in protection against the Soviet Union and communist expansionism.

The border states were interchangeably Finland, Estonia, Latvia, Lithuania, Poland, Romania and, until their annexation into the Soviet Union, short-lived Belarus and Ukraine.

At the time, Soviet foreign policy was driven by the Trotskyist idea of permanent revolution, the end goal of which was to spread communism worldwide through perpetual warfare.

In 1939, Germany and the Soviet Union signed the Molotov–Ribbentrop Pact, which included a secret clause that sanctioned the partitioning of several border states between the two regimes in the event of war.

Only nine days after the pact was signed, Nazi Germany invaded Poland, and the Soviets followed suit shortly after, beginning World War II in Europe.

British map of Europe in the immediate aftermath of World War I and the overthrow of tsarist empire in Russia (green). Among the changes were the establishment of independent states of Estonia, Latvia, Lithuania, Poland, Czechoslovakia, and Yugoslavia (right of centre)