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.