The attack came as U.S. officials were expected to hold peace talks with Ukrainian and Russian officials in the coming days.

In Russia, a major oil terminal near the port of Novorossiysk stopped operations Saturday after a strike by unmanned boats damaged one of its three mooring points, according to a statement from the Caspian Pipeline Consortium, or CPC, which owns the terminal.

"None of us really know what Zelenskyy is like operating solo, because he never has," one expert told NBC News.

Russian drone and missile attacks in and around Ukraine's capital killed at least three people early Saturday, officials said, as the country's representatives traveled to the United States to work on a renewed push to end the war.

Russian President Vladimir Putin said that a US plan to end the war in Ukraine could “form the basis for future agreements” but renewed threats to seize more territory by force unless Kyiv withdraws.

Widescale Russian attack on Ukraine kills six, injures dozens, as Kyiv seeks US support for a resolution to the war.

After working together during the successful presidential campaign of 2019, Yermak became Zelensky's chief of staff. He stood next to the president as he gave his now famous "we are still here" speech as the Russians descended on Kyiv at the start of their full-scale invasion in February 2022.

Ukraine's gas facilities have suffered severe damage from Russian drone and missile attacks, forcing the country to import more gas