Russia-Ukraine updates: US to ban Russian carriers from its airspace

Ukraine's deputy interior minister, Anton Gerashchenko, warned on Thursday afternoon that Russian and Belarusian troops have entered the deserted exclusion zone around the Chernobyl power plant, the site of the world's worst nuclear accident, located about 60 miles north of the Ukrainian capital, Kyiv.

In a statement posted on his official Facebook page, Gerashchenko said Ukrainian forces are putting up an intense resistance. The Chernobyl Exclusion Zone begins almost immediately below Ukraine's border with Belarus.

Gerashchenko expressed concerns that artillery could hit the reactor if fighting were to approach it, causing radioactive nuclear dust to spread over the region.

Ukrainian President Volodymyr Zelenskyy said Russian forces "are trying to seize" the Chernobyl Exclusion Zone.

"Our defenders are giving their lives so that the tragedy of 1986 will not be repeated," Zelenskyy said in a post on his official Twitter account Thursday. "This is a declaration of war against the whole of Europe."

-ABC News' Patrick Reevell

Russian airstrikes have destroyed 74 ground targets belonging to the Ukrainian military thus far, including 11 airfields, three command centers and a naval base, Russian Ministry of Defense spokesperson Igor Konashenkov said Thursday.

Some 18 radio-locating stations for anti-aircraft missile systems were also destroyed, according to Konashenkov.

However, Konashenkov noted that the strikes are not being carried out against social facilities at Ukrainian military garrisons, such as homes, residential buildings and barracks, in order to avoid casualties among servicemen and their families.

Meanwhile, he said a Russian assault aircraft crashed due to a "pilot error" in eastern Ukraine's Donbas region.

"The pilot safely ejected and is at his military garrison now," Konashenkov added.

Pro-Russian separatist militias in Donbas continue a counteroffensive on the Ukrainian Armed Forces with fire support from the Russian army, according to Konashenkov.

-ABC News' Tanya Stukalova

U.S. President Joe Biden met with the National Security Council on Thursday morning in the Situation Room to discuss the latest developments in Ukraine, according to a White House official.

Biden was already scheduled this week to participate in a virtual meeting of the G-7 leaders to discuss the ongoing situation as well as priorities of the German G-7 presidency year.

In the early afternoon Thursday, Biden will address the nation directly on the Russian invasion of Ukraine and announce "further consequences" that the United States and its allies will impose on Russia "for its unprovoked and unjustified attack on Ukraine," according to the White House.

U.S. Army soldiers in the 82nd Airborne Division in Poland will be deployed to the checkpoints at the border with Ukraine to help with a possible surge in the flow of traffic, a military source with direct knowledge told ABC News on Thursday.

Their new mission is a change from their previous one of solely to "deter and assure," as a full-scale Russian invasion is now underway in neighboring Ukraine.

With Ukraine's airspace shut down, the source said they expect traffic at border checkpoints to increase significantly, including citizens of NATO member states. However, estimates on the number of potential refugees was unclear.

There are currently 5,200 U.S. troops currently in Poland, with another 300 en route from Germany. Although they are on slightly higher alert, there was no expectation of any engagement with the Russian forces attacking Ukraine.

-ABC News' Matt Gutman, Tomek Rolski and Robert Zepeda