The policy tended to see the border states as a cordon sanitaire, or buffer states, separating Western Europe from the newly-formed Soviet Union. It was never particularly successful, however; disputes and different allegiances between andwithin the group of states hindered unity. The matter was further complicated by the rise of the expansionist Nazi Germany. In 1939 Germany and the Soviet Union signed the Molotov-Ribbentrop Pact, which effectively divided the territory of the border states between those two countries. With the exception of Finland, all border states fell under Soviet occupation as a result of World War II.