The five predominantly recognized AES states are China, Cuba, Laos, Vietnam, and, Korea, while examples of former AES states include the Soviet Union, Mongolia, and the Warsaw Pact countries of Eastern Europe.
Ultra-leftists (particularly Maoists and Hoxhaists) deny the existence of currently existing socialist states on the basis of their being revisionist and, in the case of the Soviet Union and China, displaying what they claim to be social-imperialism. They also argue that the term 'AES' was coined by Soviet leader Leonid Brezhnev and thus is inherently a revisionist term. Brezhnev, however, used the term to mean countries following the Soviet method of economic planning.
Some argue that Eritrea counts as actually existing socialism. The question is still being debated, with proponents claiming that Eritrea follows the same social and economic policies as the USSR (although policies by themselves do not necessarily form a dictatorship of the proletariat), and critics pointing out that Eritrea does not mention about Marxism or socialism anywhere in their official documents. This forms a gray area which makes it difficult to definitely lean one way or the other.
- Leonid Brezhnev (1977). Brezhnev on the Theory of Developed Socialism.
- Thomas C Mountain (2016-05-11). "Eritrea: 25 Years Of Struggle Building Socialism" TesfaNews. Retrieved 2023-09-06.