Russia launched a wide-ranging attack on Ukraine on Thursday, hitting cities and bases with airstrikes or shelling, as civilians piled into trains and cars to flee. Ukraine’s government said Russian tanks and troops rolled across the border in a “full-scale war” that could rewrite the geopolitical order and whose fallout already reverberated around the world.

In unleashing Moscow’s most aggressive action since the Soviet invasion of Afghanistan in 1979, President Vladimir Putin deflected global condemnation and cascading new sanctions — and chillingly referred to his country’s nuclear arsenal. He threatened any foreign country attempting to interfere with “consequences you have never seen.”

Ukraine’s president said Russian forces were trying to seize the Chernobyl nuclear plant, site of the world’s worst nuclear disaster, and Ukrainian forces were battling other troops just miles from Kyiv for control of a strategic airport. Large explosions were heard in the capital there and in other cities, and people massed in train stations and took to roads, as the government said the former Soviet republic was seeing a long-anticipated invasion from the east, north and south.

Russian troops bore down on Ukraine’s capital Friday, with gunfire and explosions resonating ever closer to the government quarter, in an invasion of a democratic country that has fueled fears of wider war in Europe and triggered worldwide efforts to make Russia stop.

With reports of hundreds of casualties from the warfare — including shelling that sliced through a Kyiv apartment building and pummeled bridges and schools — there also were growing signs that Vladimir Putin’s Russia may be seeking to overthrow Ukraine’s government. It would be his boldest effort yet to redraw the world map and revive Moscow’s Cold War-era influence.

In the fog of war, it was unclear how much of Ukraine remains under Ukrainian control and how much or little Russian forces have seized. The Kremlin accepted Kyiv’s offer to hold talks, but it appeared to be an effort to squeeze concessions out of Ukraine’s embattled president instead of a gesture toward a diplomatic solution.

President Joe Biden has selected Ketanji Brown Jackson as his nominee to the Supreme Court, setting in motion a historic confirmation process for the first Black woman to sit on the highest court in the nation.

Biden will deliver remarks on Friday afternoon announcing the selection, the White House said. CNN first reported Biden’s decision.

Jackson, 51, currently sits on DC’s federal appellate court and had been considered the front-runner for the vacancy since Justice Stephen Breyer announced his retirement.

She received and accepted Biden’s offer in a call Thursday night, a source familiar with the decision told CNN, but was present for DC Circuit Court hearings Friday morning.