It’s at this point, however, that the analogy begins to break down. Whereas Hitler was an ideologue and a charismatic movement leader, Putin is an opportunist, a political mafioso who schemed his way to power and clings to it for its own sake.

Immense as his sense of Russian grievance, or his hostility toward Muslims or gays, may be, Putin is not driven by the kind of all-encompassing racism that led Hitler to perpetrate the Holocaust, or by anything like the crazed notion of Lebensraum that motivated Hitler’s attempted conquests in the East.

Even his proposed Eurasian Union is not a sweeping ideological concept like Nazism or communism. His designs are aggressive but, in terms of Russian history and geography, traditional. They probably do not extend beyond the “near abroad.” Hitler (and, to some extent, Stalin) had ambitions in the West as well.

Unlike Hitler, Putin must temper his adventurism with due regard for a West that, however war-weary, fractious and self-absorbed it may be, is still powerful enough to cripple his economy — and still headed by a United States that possesses a nuclear deterrent and is formally committed to defend its NATO allies. (Of course, unlike Hitler, Putin has nukes, too.)