A senior U.S. defense official told reporters Friday that there is still "no appreciable movement" by a convoy of Russian forces approaching Kyiv, with the closest forces still about 25 kilometers from the city.

The official said a sabotaged bridge and Ukrainian attacks have contributed to the stalling of the convoy.

As for Kharkiv and Cherniv, the official said the U.S. estimates that Russian forces are about 10 kilometers from both city centers.

The official confirmed Russia took control of the Zaparozhye nuclear power plant.

The official said the U.S. is not in a position to independently verify that Russia has taken control of Kherson, saying fighting between the Russians and Ukrainians around the city has been seen as recently as today.

Mariupol is still under Ukrainian control, but Russians are bombarding the city and approaching from the north and up from the Azov coast, the official said.

Ukraine is still assessed to have "a strong majority" of its combat air power in tact, according to the official. Both Ukraine and Russia are also both believed to be using drones.

Russia has sent in approximately 92% of the forces it had arrayed at the border, up from about 90% yesterday, the official said.

Russians have now fired more than 500 missiles against Ukraine, according to the official.

-ABC News' Matt Seyler

The United Nations Security Council met Friday in an emergency session over Russia's attacks on Ukraine's Zaporizhzhia nuclear power plant.

The British representative said this is the first time a state has attacked a functioning nuclear power plant.

Senior U.N. diplomat and Under Secretary-General for Political Affairs Rosemary DiCarlo condemned active military activity near a nuclear site as "not only unacceptable, but highly irresponsible."

"Every action should be taken to avoid a catastrophic nuclear incident," she added, saying an attack on a functioning nuclear power plant is contrary to international humanitarian law.

-ABC News' Conor Finnegan

A new Russian law could send people to prison for up to 15 years for posting "fake news" about the war.

Journalists and media in Russia will now only be able to report what is happening as the Kremlin reports it.

Duma, Russia's legislative body, passed the rule Friday. It will be sent to Russian President Vladimir Putin's desk for it to be signed into law.

-ABC News' Tanaya Stukalova

The Arctic Council on Friday said it would boycott future talks with Russia over its invasion of Ukraine. Russia currently holds the chairmanship until 2023, according to a report by Reuters.

The intergovernmental forum is designed to promote cooperation between the eight Arctic states of Canada, Denmark, Finland, Iceland, Norway, Russia, Sweden and the U.S.

The council said it is canceling all of its official meetings, including those of its subsidiary bodies, until further notice. Its next meeting was scheduled in Russia this May.

This comes at a sensitive time when climate change is opening up the Arctic to resource exploitation.

-ABC News' Tracy Wholf

The United Nations High Commissioner for Human Rights has "received credible reports of several cases of Russian forces using cluster munitions, including in populated areas," spokesperson Elizabeth Throssell said Friday.

"Due to their wide-area effects, the use of cluster munitions in populated areas is incompatible with international humanitarian law principles," Throssell said.

Throssell added, "We remind Russian authorities that directing attacks against civilians and civilian objects as well as so-called bombardment in towns and villages and other forms of indiscriminate attacks are prohibited under international law and may amount to war crimes."

To date, there have been 26 attacks on health care facilities in Ukraine, killing at least 12 people and injuring 34 people, according to Jašarević. Two of those killed and eight of the injured were healthcare workers.

That number is "shocking," said Throssell.

Throssell and WHO spokesperson Tarik Jašarević declined to pin the blame for all of them on Russia.

This number of attacks includes Wednesday's strike on a children's hospital and maternity ward in Mariupol. On Thursday, Russian officials claimed that the attack was staged, but they first confirmed they bombed it and claimed the hospital was being used by Ukrainian "radicals."

Throssell told reporters that is not true; "It was a functioning hospital," she said.

-ABC News' Conor Finnegan