KIEV, Ukraine — The word “maidan” means “square” in Ukrainian and in Arabic. And the “Independence Maidan” of Kiev, like the “Tahrir Maidan” of Cairo, has been the scene of an awe-inspiring burst of democratic aspirations. The barricades of piled cobblestones, tires, wood beams and burned cars erected by Ukrainian revolutionaries are still there — indeed, it looks as if it could be the set of “Les Misérables” — and people still lay fresh flowers at the makeshift shrines for the more than 100 people killed in the Maidan by the old and now deposed regime here. Walking through it, though, I tried to explain to my host that, while I was incredibly impressed, a lot of Americans today have “Maidan fatigue” — too many dashed hopes for democracy in too many squares — from Afghanistan to Iran, Iraq to Egypt, Syria to Libya.

Get over it, Ukrainians tell me. Our revolution is different. There are real democratic roots here, real civil society institutions and the magnet of the European Union next door. With a little help, we can do this.

The more I learn here, the more I think they’re right. Something very consequential has happened here. In fact, I think the future of Ukraine is one of the most consequential foreign policy challenges of the Obama presidency because it will not only determine the future of Ukraine but of Russia.

It would have been nice if we could have forged a compromise with President Vladimir Putin of Russia that would have allowed Ukraine to gradually join the European Union and not threaten him. President Obama tried to find such a win-win formula. But Putin is not into win-win here. He is into win-lose. So he must lose, for the sake of Ukraine and Russia.

That won’t be a cakewalk. We and our European allies will have to overcome our fatigue, and Ukrainians will have to unite more than ever. The first test will come on May 25 when Ukraine holds presidential elections. Putin is working to prevent or discredit those elections by bombarding the more pro-Russian eastern Ukraine with propaganda that the Maidan movement was led by “fascists” and using his agents and hooded local thugs to keep the region in turmoil so people won’t vote.

Our job is to back Putin off so the elections can happen. That may require more sanctions right now. The Ukrainians’ job is to make sure elections are relevant by electing a decent, inclusive person, who will work to ensure Ukraine’s unity and clean up its corruption. We can deter Putin, but only Ukrainians can threaten his legitimacy. If a majority here votes in a free election to move toward Europe and away from Moscow, Putin has a real problem. It is a huge rebuke of his warped vision, coming from right next door.

Daria Marchak, a young business reporter here, explained to me why young Ukrainians are so desperate to join the E.U. “Up to 2011, there was a sense of improvement here,” she said. But the last government was so corrupt, at an industrial scale, people felt “we were going backward.” And then when that old government said it was abandoning the idea of joining the E.U. to join Putin’s bogus Eurasian Union, it was the last straw.

“People felt that if we joined Putin’s customs union the corrupt system here will be cemented forever,” said Marchak, and young people would have no future. Their desperation to join the European Union is in the hope that it will lead to what I call “globalution” — revolution from beyond — that the E.U. will force on Ukraine’s politicians standards of transparency that the young people here simply can’t. The E.U. “will be the instrument of change,” she said.

But for Ukraine to unite and join the E.U. will require a president with an inclusive vision for integrating the East and West of this country, said Oleh Levchenko, a Maidan political activist.

“The biggest problem we have today is the absence of the right message — a message that can unite East and West,” he said. “So this is not a problem of Putin. It is our failure. Nobody draws a unifying vision of the future.”

Indeed, Ukraine has some “Tahrir Square disease.” The Kiev revolutionaries have been incredibly brave. But, like in Egypt, they have not yet translated their aspirations — for an inclusive, noncorrupt, pro-E.U. future — into their own political parties or national candidates who can win elections and govern. So old oligarchs are filling the void. Some are actually decent, but Ukraine has to do better.

Olena Litvishko, of the Ukrainian Initiative for Peaceful Protest, told me that what the Maidan revolution did was elevate “a strata of civil society and business who have the energy for change, but not the instruments for change.” They don’t have real political parties based on a broad shared agenda. “They don’t know their rights, and our politicians don’t want them to.”

In sum, it was courageous Ukrainians who gave birth to their own clean democracy movement, because they were fed up. But Putin can’t live with a successful, Westward-looking democracy here, and young Ukrainians can’t live without it. So, for it to thrive, we have to make sure Putin doesn’t kill it in the crib, and they have to make sure their old-line politicians don’t kill it before it learns to walk.