Socialism in one country is certainly possible, Communism must be global. This has always been the case, and historical practice affirms this. The Trotskyist assertion needs to actually be backed by analysis, in the time of Trotsky support for Permanent Revolution came because of a lack of faith in the Peasantry, such issues are not the same in the PRC and moreover the Peasantry has been shown to authentically align with the Proletariat.