It isn't fair or accurate to say that. Despite the interference from capitalist countries like the U.S.A, there have been, and currently are, countries that not only embraced socialism, but were in fact socialist, such as the former Soviet Union or modern-day Cuba.
@Radical_EgoCom @FisherPeter
Not denying their existence. I am just saying it's hard to measure how successful they are given the amount of interference they have had to endure.