President Obama’s reaction to Russia’s bullying of Ukraine and its illegal occupation of Crimea isn’t bad, so far. The sanctions that he’s ordered against various Russian officials, including those in Vladimir Putin’s inner circle, are measured. And he’s ignored or rejected calls from hardliners, hawks and neoconservatives, so far, to up the ante by pledging to expand NATO to Ukraine and Georgia, rush weapons to the new government in Kiev, send the US naval fleet into the Black Sea, install anti-missile defense systems in eastern Europe and so forth. (Senator John McCain, who never misses a chance to be recklessly provocative, has demanded installing a missile defense system in Poland and the Czech Republic, bringing Moldova and Georgia into NATO, rushing arms to Ukraine and more.)

But the widely expected result of the Crimean referendum on Sunday, which overwhelmingly backed unification with Russia, presents a challenge for Obama, one that will require a great deal of skill and forbearance to navigate successfully.

Both Obama and Secretary of State John Kerry continue to emphasize that Putin has a face-saving off-ramp if he seeks to extricate himself from the Crimean region.

But it isn’t clear that Putin is interested in any off-ramps. Why not? Maybe it’s because the Russian president thinks that just as he used the war in Chechnya in 1999 to help catapult himself to power by rallying nationalists behind him, now he can ride another wave of Russian nationalism by proclaiming himself as the Great Liberator of Crimea. Maybe it’s because he really and truly believes that taking Crimea is the first step toward restoring Russia’s faded glory. Maybe it’s because Putin is building ties with the fanatical, reactionary Russian Orthodox Church, with its anti-homosexual passions and its reverential belief that modern Russia started with the Christianization of the Kievan Rus by Prince Vladimir from 988 AD, and Putin wants to cast himself as the new Prince Vladimir. Or maybe it’s because Putin is seething over the fall of the Soviet Union and the ill-considered Westernization (and NATO-ization) of Eastern Europe since the 1990s. Whatever the reason, it seems likely that Putin is not going to give up Crimea, and that he’ll keep up the pressure on Kiev—perhaps through the creeping destabilization of eastern Ukraine, the phony talk of “protecting” ethnic Russians and Russian-speaking Ukrainians there and the gradual bolstering of pro-Russian militias in parts of Ukraine that border Russia.

If so, we’re in for a bumpy ride.

Few Americans are truly concerned about Ukraine, nor should they be. The United States has no real national interests there, and whether all or part of Ukraine and its Crimean region are part of Russia is irrelevant to broader US national security issues. Practically speaking, however, annexation of Crimea by Russia, and especially a further push by Moscow into Ukraine, will poison US-Russian relations for many, many years to come, and it will make cooperating with Russia on Syria, Iran and Afghanistan much more complicated than it already is. So the cause for concern is that ill will between Washington and Moscow and a spiraling down of relations will have a devastating ripple effect on much else in international relations. It will also intensify pressure on the White House to halt the cuts in the Pentagon’s budget that Obama and Secretary of Defense Hagel have already proposed, and it will provide an opening for McCain and his merry flock of hawks to demand that the United States deploy its military eastward in Europe.

A true political and economic break with Russia is extrmeley unlikely, as I wrote last week in my analysis of the capitalist ties between Russia and, especially, Western Europe.

Still, it’s worrying that Russia is suppressing dissent inside the country, shutting down Russian news organizations and websites that haven’t bought into Putin’s grandiose notions about Russian-Crimean unity. It’s worrying that Russia is reportedly sending covert forces into eastern Ukraine to rev up anti-Kiev forces there. It’s worrying when Russian officials hint that Moscow might cancel or suspend arms agreements already reached with the United States. And it’s absurdly out of bounds when a very influential Russian propagandist takes the opportunity to remind his listeners that Russia is “the only country in the world capable of turning the U.S.A. into radioactive dust.”

It’s all grist for McCain and Co., and it isn’t clear how long Obama will resist stronger measures.