The UN now says more than 2.5 million people have fled Ukraine, most of them to Poland. NPR's Ari Shapiro reports on the busiest and one of the most quiet border crossings in Poland.

NPR's Ari Shapiro speaks with Mayor Wojciech Bakun of the city of Przemysl about being the spot in Poland where the most Ukrainians have entered as they flee their country.

In Lublin, Poland, a decades-old building has taken on a purpose its designers could never have imagined. Members of the Jewish community say this may have been the building's purpose all along.

NPR's Ari Shapiro talks with Camilla Nielsson about her new documentary President. It follows the underdog opposition candidate throughout Zimbabwe's first election after the ouster of Robert Mugabe.

A college student in Ukraine's Kherson region is worried after seeing that Russia had taken several towns in the area.

When 22-year-old college student Vitaliy Shutov went to bed last night, he didn't think a Russian invasion of Ukraine would actually happen. Then he woke to the sounds of explosions.

Three decades ago, the newly independent country of Ukraine was briefly the third-largest nuclear power in the world. A lot has changed since then.

In the borderlands near Crimea, there is a war for the hearts and minds of Ukrainian citizens.

An underground world in the Ukraine capital is made up of Soviet-era bomb shelters, bunkers and basements. A potential Russian attack threatens to put the bygone shelter system to the test.

NPR travelled towards the "temporarily occupied territories" on the Ukraine-Russia border, where the people who live there are in limbo – cut off from both Ukraine and Russia, cut off from the world.

The standoff between Ukraine and Russia is about global security and an attempt to "rewrite rules on which the world is based," says Ukraine's foreign minister.

NPR's Mary Louise Kelly reports from Donbas region of Ukraine as its residents live under the threat of a Russian incursion and cope with eight years of tensions and fighting along the border.

Russia is threatening to invade Ukraine. But in the eastern region of Donbas, war has been underway since Russia-backed separatists moved in and declared breakaway republics in 2014.

It Russia takes the path of aggression, it will face "extremely severe consequences immediately," says the U.S. charge d'affaires Kristina Kvien.

NPR's Mary Louise Kelly talks with Congressmen Gregory Meeks, D-N.Y., and Congressman Mark Green, R-Tenn., about their trip to Ukraine as the country faces the threat of a Russian invasion.

NPR's Mary Louise Kelly talks with Hanna Hopko, an original leader of Ukraine's EuroMaidan protests in 2014 about whether Ukrainians can stand up to the threat of Russian aggression.

NPR's Mary Louise Kelly talks with Kristina Kvien who, as the Charge d'Affaires at the U.S. Embassy in Ukraine, is the top American official on the ground in Kyiv.

Amid the crisis with Russia, some Ukrainians say their president has come up short. Others, like some of the ones skating in front of the office of the president, say they still support him.

Ukraine's former prime minister Arseniy Yatsenyuk says the military is stronger than it was the last time Russia invaded in 2014. But he still thinks the U.S. should help should Russia make advances.

NPR's Mary Louise Kelly talks with people in Kyiv about the possibility of a Russian invasion into Ukraine.