That final scenario should particularly concern Putin. Although neither the United States nor NATO has any appetite to intervene militarily to save Ukraine from a Soviet invasion, they would not be averse to aiding a likely Ukrainian partisan guerrilla war against a hostile occupying army—which history suggests could be prolonged and substantial, as Adolf Hitler’s forces discovered during World War II. The Ukrainians appear far more ready and willing to fight than, for example, the Czechoslovaks were in 1968.

Of course, Putin evidently feels entitled to seize (or, in his Soviet-rooted view, reconquer) Ukraine because, unlike Hungary and Poland, it is a former republic of the Soviet Union and historically, ethnically, and linguistically closely tied to Russia. Yet the rest of the world (and even Russia itself, in a 1994 agreement) has recognized Ukraine’s sovereignty as an independent nation following the Soviet collapse. Many Ukrainians recall angrily how Moscow egregiously mistreated their country when it was incorporated into the Soviet Union; the great manmade famine that killed millions of Ukrainians during Stalin’s rule in the 1930s looms large in the country’s public consciousness. Such historical memories could underpin violent resistance to Russian occupation.

Russia’s attack on Ukraine will likely accelerate the outcome he wants least: a bigger and stronger NATO. After the chaos of the Donald Trump presidency, the alliance tightened ranks in a bid to deter Putin from launching an assault on Ukraine. Countries along or near the Russian periphery that value their independence but do not yet belong to NATO may now seriously consider joining or intensify their efforts to do so. Potential new members could expand beyond former Soviet republics to include countries that remained neutral during the Cold War, either voluntarily (such as Sweden) or as a result of Soviet coercion (such as Austria and Finland). Already, some Finns are publicly musing about un-“Finlandizing” and abandoning their traditional distance from NATO.