Military analysts say Russia is pulling away from areas around Kyiv, the capital, though the Pentagon has cautioned that it could be regrouping. The Red Cross is trying again to reach the besieged city of Mariupol.

Russian troops are in retreat from the areas surrounding Kyiv, the Ukrainian capital, military analysts and Ukrainian officials say, a potentially stunning reversal in what could signal a broader shift in Russia’s assault in the sixth week of war.

It is unclear whether the Russian troops are gone from the areas near the capital and further north for good or are trying to regroup after weeks of intense Ukrainian resistance and crippling logistical failures. But they appear, at least for now, to be following through on Russia’s stated intentions to focus more on the east, where they have a strong foothold and where military analysts said they were already scaling up their attacks.

For Kyiv, the retreat comes after early anxiety that the tanks gathering outside the city and pummeling nearby suburbs would advance into the city. According to the latest British defense intelligence assessment, Ukrainian forces are continuing to advance against the withdrawing Russian forces.

Russian forces are reported to have withdrawn from nearby Hostomel airport, which had been the center of fierce fighting since the start of the invasion, the assessment added. New satellite images appeared to show that Russian military equipment had been removed in recent days from the airfield.

In the eastern part of the country, Russia’s main efforts are now focused on capturing the port city of Mariupol and solidifying control of the Donetsk and Luhansk regions, according to an analysis from the Institute for the Study of War, a Washington think tank. Local officials on Saturday said that fighting had intensified in some parts of the region.

A humanitarian convoy was set to try again on Saturday to deliver aid to the besieged southern city of Mariupol and help evacuate more people. The aid group had not been given the security guarantee it needed to make it to Mariupol on Friday, despite earlier Russian pledges to establish a cease-fire and a humanitarian corridor.

In other developments:

  • The Pentagon provided Congress with details on $300 million in military assistance that it will give Ukraine. The list of weapons includes laser-guided rockets, tactical drones and “nonstandard” weapons and ammunition — a term that the Defense Department typically uses to refer to Soviet-designed weapons like those used by Ukrainian troops.
  • Pope Francis, arriving in Malta for a short trip drawing attention to the plight of migrants, inched closer on Saturday to blaming President Vladimir V. Putin of Russia for the war in Ukraine. He also said a potential papal visit to Kyiv was “on the table.” 
  • Russia will end its cooperation on the International Space Station program, the head of its space agency said in a post on the Telegram social media app on Saturday. He blamed sanctions imposed on Russia for the decision.
  • The death toll from a Russian missile strike on a government building in the southern city of Mykolaiv this week has risen to 33, Ukraine’s emergency service said on Saturday.