President John F. Kennedy memorably called the Cold War a “long, twilight struggle”- the four-decade contest in Europe for freedom and power between the United States and Soviet Union. Last week’s dramatic revolution in Ukraine was compelling evidence that Cold War passions continue to burn in a country deeply divided between East and West.

It is too early to predict where these momentous events will carry the people of Ukraine. The new interim government, dominated by nationalists from the central and western parts of Ukraine, acted swiftly to set presidential elections in May and seek greater economic and political ties with Europe. But in the industrialized country’s east and south, millions of ethnic Russians want to maintain Ukraine’s centuries-old symbiotic cultural, linguistic, and economic links to Russia.

One thing is certain-Russian President Vladimir Putin will not easily accept Ukraine’s separation from Moscow. He will push back hard to keep Ukraine within the Kremlin’s orbit. It is unlikely in the short term that Russian tanks will roll across the border to defend ethnic Russians in Donetsk, Kharkiv, and the Crimea. Instead, his instinct will be to use Russia’s stranglehold on the Ukrainian economy to intimidate, if not blackmail, the interim rulers in Kiev. Putin has turned off Russia’s natural gas spigot in the past and may do so again.

President Obama is thus right to proceed cautiously given the risk of conflict with Moscow. But Ukraine matters to American interests, too.

Every president since Harry Truman has viewed a democratic, free Europe as one of America’s most vital strategic aims. President George H.W. Bush described it as a Europe “whole, free, and at peace.” It was the absence of such a Europe that compelled our entry into the First and Second World Wars and the long Cold War.

Don’t look, however, for a repetition of the old Cold War strategy as the Obama team prepares to duel with Putin. The United States will not deploy military forces on the front lines of a new East-West divide. Instead, it is countering with a more patient diplomatic strategy to help Ukraine steer clear of Moscow’s smothering embrace. In the last few days, the United States and Europe have stressed the importance of an independent, undivided Ukraine built by free elections and peaceful change. Obama is challenging Russia to join a global financial effort to rescue Ukraine’s nearly bankrupt economy. He should also push the interim government to reach out to distrustful ethnic Russians in eastern Ukraine. All this will help to build global pressure on Putin not to deploy military force. But Obama will need to lead this effort.

Obama’s hand is also strengthened in the chess match with Putin by the prescience of Presidents Bill Clinton and George W. Bush, whose expansion of NATO to take in 10 Central European countries was criticized by some as excessively provocative to Moscow. But NATO’s push eastward has protected those countries from Putin’s aggressive muscle-flexing in Russia’s so-called “near abroad.” Lying outside of NATO and EU territory, however, Ukraine finds itself in a renewed Cold War struggle between East and West. If the United States and Europe have their way, this battle will not be decided by armies but by a persistently powerful ideal. Shouldn’t all Europeans, including the people of Ukraine, be free to choose their own future?

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Nicholas Burns is a professor of the practice of diplomacy and international politics at Harvard’s Kennedy School of Government.

Editorial, Pages 14 on 02/27/2014