I am not convinced that international class war should be practiced, especially in the modern era. The reality is that countries where a socialist revolution succeeds will most likely be economically malnourished; so, instead of publicly waging class war on nearly every country in the world and letting yourself be isolated and slowly asphyxiated, it's better to work with these nations to some extent and acquire the appropriate technological know-how and other means of production. Proletarian internationalism, in the form of making donations to people-centric governments or sending rescue teams after some natural disaster, is acceptable; however, military alliances and other burdening constraints based on ideology should be avoided at all costs.
As for China, I would say that it's socialist because of instead sharpening the contradictions between capital and labour as what is occurring in countries, like the US, the Chinese state is resolving them to their logical conclusions. The most important aspect of this is preventing the move from the real economy of industrial production and consumption to the fictitious financial economy, like what exists in the US. For example, the de-industrialization of the US primarily occurred because of the antagonism between decreasing amount of profit and rising wages, but this is not what is occurring in China. Instead of exporting all low-value manufacturing to poorer nations so monopolies can make even more profit, the Chinese central government is automating that level of manufacturing and taking away the privileges that the domestic industrialists have enjoyed so far; thus, we can see that the primary internal contradictions are slowly being resolved, and that China is increasingly heading into the type of classless and harmonious society that was described by Marx and Engels.