We cannot know this for certain, of course, but based on his writings, I rather think he would not have taken the side of the West in arguing for the inviolability of interstate boundaries. This is from his book, The Russian Question at the End of the Twentieth Century:
Russia has truly fallen into a torn state: 24 million have found themselves “abroad” without moving anywhere, by staying on the lands of their fathers and grandfathers. Twenty-five million – the largest diaspora in the world by far; how dare we turn our back to it?? – especially since local nationalisms (which we have grown accustomed to view as quite understandable, forgivable, and “progressive”) are everywhere suppressing and maltreating our severed compatriots.
Along with this awareness of the ethnic Russian diaspora in the so-called Near Abroad, Solzhenitsyn had already expressly favored a political union of the three Slavic republics in his Rebuilding Russia. Ukrainians, he opined there, should not be forced into such a “Russian Union,” but separation of Ukraine from Russia, if it were to come to that, should be settled only on the local, rather than the republican, level. One assumes this would entail allowing those parts of Ukraine, including Crimea, that feel themselves to be more Russian than Western, to stay with the larger Russian Union, if they so desire, while permitting the more nationalistic oblasts in the west to go their own way.
Solzhenitsyn explicitly addresses the plight of ethnic Russians in Ukraine, calling attention to what he sees as their mistreatment at the hands of those who would proclaim: “Ukraine for the Ukrainians!”
A sizeable portion of the ethnic Ukrainian population itself does not even use or have command of the Ukrainian language. (The native language for 63 percent of the population is Russian, while ethnic Russians make up only 22 percent of the population; i.e., in Ukraine, for every Russian there are two “non-Russians” who nonetheless consider Russian to be their mother tongue!) (Russian Question, 91)
Add to this his reference to “the false Leninist borders of Ukraine (including even the Crimean dowry of the petty tyrant Khrushchov)” (90), and we can be reasonably confident that the famed Russian author would be squarely on the side of Vladimir Putin.
I am reluctant to conclude too quickly that Solzhenitsyn would be guilty of the sin to which his colleague Evgeny Barabanov pointed decades ago when he stated that “we shall be obliged to acknowledge that in Byzantium and Russia ideas about the Kingdom of God and the kingdom of Caesar too often merged and became interchangeable.” But Solzhenitsyn’s nationalism was his great blind spot.
The late Orthodox theologian, Fr. Alexander Schmemann, had wide-ranging discussions with the novelist in the mid-1970s and made some revealing observations on this encounter in his personal journals. Among other things Schmemann wrote of
Solzhenitsyn’s “idolizing obsession with Russia” (p. 65). “For [Solzhenitsyn] there is only Russia. For me, Russia could disappear, die, and nothing would change in my fundamental vision of the world. ‘The image of the world is passing.’ This tonality of Christianity is quite foreign to him” (p. 61).
While one can understand Solzhenitsyn’s concern for ethnic Russian minorities, his nationalism is off-putting. Changing interstate boundaries at the whim of the powerful, however strong the justification might be for territorial adjustments, is a recipe for the sort of irredentist bloodletting that marred the first half of the twentieth century, in which Solzhenitsyn himself was caught up.
Yet even our greatest heroes usually distinguish themselves in one area for which they properly earn recognition. Much as we do not look to the great scientists and inventors to produce great poetry or art, so we read Solzhenitsyn, not for his expertise in international relations, but for his considerable insight into the human condition and into a world that has largely forgotten its dependence on God.