By 1921 it had become clear to all but the more incorrigible optimists that there would be no repetition of October 1917 anywhere else and that for an indeterminate period the revolution would remain confined to Russia and her possessions. The concept of 'socialism in one country' was not launched by Stalin in his conflict with Trotsky, but earlier by Lenin himself.
p. 72 - Three Whys of the Russian Revolution (1995)