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

U.S. Secretary of State Antony Blinken crossed the border into Ukraine Saturday after meeting with Ukrainian Foreign Minister Dmytro Kuleba at the Korczowa Border Crossing Point.

"The entire world stand with Ukraine," Blinken said, and Kuleba added that he hopes Ukrainians will see this as a "clear manifestation that we have friends who literally stand by us."

Blinken said the sanctions imposed so far against Russia are "producing very, very concrete results" and that the pressure will "grow" until this "war of choice is brought to an end."

When asked directly about helping Kuleba with more firepower, Blinken said, "the support for Ukraine not only has been unprecedented, not only is going to continue, it's going to increase."

Kuleba said Ukraine "appreciates" sanctions that have been announced in the last week, but that more economic and political pressure and "necessary weapons," would "save many lives in Ukraine... many sufferings will be avoided."

Kuleba also said that they are “satisfied" with already arranged supplies of anti-tank weapons and ammunition, but that “it’s no secret” they still want fighter jets and air defense systems.

He also thanked the U.S. for sending stingers, and said they were used on Saturday.

"Just today we shot down three Russian attack aircrafts, which were bombing our cities with the use of stingers but we need -- so to say -- big air defense systems to ensure the safety of our skies. If we lose the skies, there will be much, much more blood on the ground,"Kuleba said.

In response to questions about NATO’s refusal to impose a no-fly zone over Ukraine, Kuleba said it’s a "sign of weakness," but stayed optimistic that they will change their minds.

"The time will come," he said.

-ABC News' Conor Finnegan and Justin Gomez