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

After Russian forces seized the area around the Chernobyl nuclear power station, the facilities continue "to operate safely and securely," Ukraine's regulatory agency informed the International Atomic Energy Agency, the U.N. Nuclear watchdog said Friday. 

There were slightly higher levels of radiation, but they are still "low and remain within the operational range measured in the Exclusion Zone since it was established, and therefore do not pose any danger to the public," the IAEA said. 

One theory why the levels could have ticked up, according to the IAEA, is "heavy military vehicles stirring up soil still contaminated from the 1986 accident." 

The Chernobyl power plant, the site of the world's worst nuclear accident, is located about 60 miles north of the Ukrainian capital, Kyiv. The Chernobyl exclusion zone begins almost immediately below Ukraine's border with Belarus. 

The Russian Ministry of Defense said Friday that Russian troops took full control of the Chernobyl plant area on Thursday.

-ABC News' Conor Finnegan

A senior defense official confirms that there is a Russian "amphibious assault" underway along the Ukrainian coast from the Sea of Azov. The attack is to the west of Mariupol, which is a coastal city in southeastern Ukraine.

"Indications are right now that they are putting potentially thousands of naval infantry ashore there," the official said. 

The push toward Kyiv is going slower than the Russians expected as they're meeting more resistance from Ukrainians than they thought, the official said.

“In general the Russians have lost a little bit of their momentum," the official said.

The official pointed out that no population centers have been taken and the Russians do not have air superiority over Ukraine as Ukrainian air defenses are still working.

The official said more than 200 ballistic and cruise missiles have been fired at targets in Ukraine, adding some have "impacted civilian residential areas."

The U.S. assesses that "a third of the combat power " of the 150,000 Russian troops that were amassed on border are actually dedicated to the fighting in Ukraine, according to the official. “They have not they have not committed the majority of their forces inside Ukraine," the official said.

Fighting is also underway at the Kakhovka hydroelectric power plant and dam on the Dnieper River that controls a lot of electrical power to Crimea and southern Ukraine, the official said, adding that there have been cyberattacks against power plants.

-ABC News' Matt Seyler, Luis Martinez

There was an eerie quietness across Kyiv on Friday afternoon, as Russian forces closed in on the Ukrainian capital.

A senior U.S. official told ABC News that he believes the pause around Kyiv was due to the Russian military reinforcing troops and resupplying ammunition and food, and that Russia still wants a stranglehold on the city over the next 24 to 48 hours.

The official also expressed great concern about civilian causalities if Russian forces do move in. While there appeared to be a renewed effort at diplomacy on Friday, the United States believes any noise Russia makes about negotiations is simply stalling, the official said.

-ABC News' Martha Raddatz

Russia claimed Friday that Ukrainian President Volodymyr Zelenskyy has agreed to discuss neutrality for his country.

"Zelenskyy stated his readiness to discuss the neutral status of Ukraine," Kremlin spokesman Dmitry Peskov told reporters during a daily call. "From the beginning, Russia's President Vladimir Putin spoke about how the goal of the operation to the [separatist regions], including a path to the demilitarisation and de-Nazification of Ukraine. But that is actually also an essential component of neutral status."

Peskov added that Putin is prepared to send a delegation to neighboring Belarus to hold talks with Ukrainian officials in Minsk.

If the Kremlin's claims are true, it would amount to Zelenskyy surrendering to Russia's demand that Ukraine pledges to never join NATO.

Earlier Friday, Zelenskyy called on Putin to hold talks "to stop people dying." But he did not mention neutral status.

The comments came as Russian troops reached the center of Ukraine's capital, Kyiv, and engaged in fighting with Ukrainian troops.

-ABC News' Patrick Reevell