The article analyses one of the main elements of the Soviet political doctrine, as well as the principles of Soviet education -- internationalism and its implementation at school. Internationalist upbringing and the accompanying "friendship of nations" become the main axis of this article, not only in terms of the concepts themselves and their ideologised meanings, but also, and most importantly, in terms of their expressions, which are presented based on the interviews of 32 former students about their experiences in the Lithuanian Soviet school in the late Soviet era (1960s-1980s). In this case, the most striking aspect of the introduction of the so-called "friendship of nations" in schools is the example of pupils' correspondence with young people from different socialist countries and Soviet republics. Relying on the personal reflections of pupils at the time, and also on the Soviet press, textbooks, etc., we analyse what promoted and what constrained this form of communication. The study reveals that internationalist education served as a Trojan horse, masking russification and the ideology of the "creation of a new Soviet man".