For a historical view on the Ukraine crisis, NPR's Leila Fadel talks to Mary Elise Sarotte, professor of history at Johns Hopkins University School of Advanced International Studies.

LEILA FADEL, HOST:

To really grasp what's going on at the border of Russia and Ukraine, it helps to know some history. We've called on Mary Elise Sarotte. She's a professor of history at Johns Hopkins University School of Advanced International Studies. Her latest book is "Not One Inch: America, Russia, And The Making Of Post-Cold War Stalemate." Thanks for being on the program, Mary Elise.

MARY ELISE SAROTTE: Thank you so much.

FADEL: So let's go back in time. The Soviet Union falls. There's this moment of opportunity for the U.S.-Russia relationship. Ukraine becomes an independent state. Take us back to that time.

SAROTTE: Yes. As President Bill Clinton said in the early 1990s, it was the first chance ever since the rise of the nation-state to have the entire continent of Europe live in peace. But the big question mark was - what would happen to the Soviet strategic nuclear arsenal? What would happen after the collapse of centralized control and command? And Ukraine was particularly important because due to the amount of former Soviet arsenal on its territory, once it became independent, Ukraine was born nuclear. It was born the third-biggest nuclear power in the world.

FADEL: Right. So that's the reason that Ukraine becomes so strategic and the West wants to bring Ukraine into their sphere of influence.

SAROTTE: Yes, that and the fact that Ukraine is a large country. At that point, it had more than 50 million inhabitants. It was becoming a democracy. It's clearly a major European country. So you want to define a place for it in post-Cold War Europe.

FADEL: So what becomes of this moment of opportunity?

SAROTTE: As a historian, I know that Cold Wars are not short-lived affairs.