Genuine internationalism stems from equal footing and the right to self-determination of all communities of people, or all "nations." To quote the relevant bit from Stalin, "a nation is a historically constituted, stable community of people, formed on the basis of a common language, territory, economic life and culture." When I say that the self-determination of all nations is critical for internationalism, I mean this in a similar reason for why I support the working class. I am not opposed to the individuals within them, it's a recognition of the struggle for national liberation, such as the ongoing struggle for self-determination in Palestine.

In Marxist philosophy, there are primary and secondary contradictions. Combatting secondary contradictions that rest on the primary contradiction also combats the primary contradiction. The struggle for national liberation is like the struggle for women's liberation, for queer liberation: secondary contradictions that rest upon the primary contradiction of class struggle. They are all inter-linked, and as such when we fight for self-determination against colonialism, we also fight capitalism at the same time. Nationalism switches from being progressive to being reactionary when it is used to justify support for colonizers and imperialists.

I call myself a Marxist-Leninist because I am an internationalist, a follower of Marx, Engels, and Lenin. Stalin did not invent the national question, he did work on it that Lenin acknowledged as correct, and whose views they sharpened against each other. The nation was not invented by Stalin, it was understood by Marx in his support of Ireland and Poland against colonialism, refined by Lenin in his support for self-determination of all peoples, and further codified and studied by Stalin, who was a national minority within the Russian Empire himself as a Georgian.

So, in essense, Stalin did not invent anything new, he merely extended and theorized upon Lenin's advancements. It is for the same reason that we do not always tack on any individual theorist as an "-ism," for example Marxist-Leninists appreciate Mao's contributions, but do not believe them to represent a universal or new advancement upon Marxism-Leninism.