The year 1917 was a momentous one in the history of the twentieth century. It was the year when the two great extra-European powers—the Soviet Union and the United States—stepped into the mainstream of history to proclaim two rival world ideologies. The United States, under President Wilson, entered the First World War not to restore the balance of power but to end the whole European state system and ‘make the world safe for democracy’ under a new international order. Russia, under the leadership of Lenin, had the Bolshevik Revolution, withdrew from the war and called for a ‘world’ revolution. There is a sense, ideologically speaking, in which it is accurate to speak of the cold war beginning in 1917. The full impact of these two events, however, was not to be felt until after 1945, when political power moved from the centre of Europe to Moscow and Washington.
There are three main sources of Soviet foreign policy. First is the historical experience of Tsarist Russia before 1917. Since the seventeenth century Russia had been subject to attack and invasion, especially from the West, and therefore always felt insecure. Second, after the Bolshevik Revolution of 1917 Russia dropped out of the First World War and was subsequently