However, it is quite possible that Stalin overstated the probability of war deliberately to push through his ambitions and to strengthen his personal power within the party. Stalin's socialism in one country' had mixed support with some communists siding with it and other preferring the idea of spreading the revolution as promoted by Trotsky. With Trotsky exiled and his leftist supporters scattered, it was easier for Stalin to use their ideas for industrialisation without losing his rightist support for socialism in one country' but only if Stalin could justify his position to the officials who wanted to keep the N.E.P. By doing this with the argument of war Stalin kept his rightist support and reunited the Communist party behind the Five Year Plans, massively increasing Stalin's personal power whilst discarding the rightist's power. The fact that when in 1941, the Soviet Union was almost smashed by Hitler's blitzkrieg supports the idea that Stalin didn't actually take the threat of invasion seriously and was in fact using it entirely for his own glorification. .
There were also economic reasons to embark on wide scale rapid industrialisation as Stalin proposed. Under the N.E.P industrial production was very disappointing to many communists. By 1926, pre war production levels had only just been achieved after the huge damage to Russia's infrastructure inflicted by the First World War and the civil war. Many services still remained haphazard and the country was still incredibly backwards. Since the revolution, trade with the outside world had been severely reduced and the U.S.S.R had to rely almost entirely on its own resources to industrialise. It was generally perceived that only absolute state control such as that proposed by Stalin's five year plans would manage these resources well enough to achieve the industrialisation wanted by many communists. .
However, the economic reasons were secondary to the political needs of the communism.