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.

Russian forces strafed Ukraine’s capital with a major missile barrage overnight, killing at least three people and causing widespread power outages, as the US ramps up pressure on President Volodymyr Zelenskiy to agree to concessions in the almost four-year-old war.

"Nobody will make concessions on the territories, because it’s our land and we stand here," one soldier told NBC News about the proposal's call for Ukraine to cede land to Russia.

The two oil tankers, identified as the Kairos and Virat, were empty and sailing to Novorossiysk, a major Russian Black Sea oil terminal.

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.

Andriy Yermak, who served as Ukrainian President Volodymyr Zelensky’s chief aide, submitted his resignation hours after Ukrainian’s state corruption investigators searched his residence in the early hours of the morning.

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