Ukrainian tanks move into the Donetsk region in eastern Ukraine on Monday. Francisco Seco/Associated Press

Russian forces now control “around half” of Severodonetsk, one of the last major Ukrainian-held areas of the country’s eastern Luhansk region, local officials said. Capturing the whole city would be a major symbolic victory for Russia. Ukrainian President Volodymyr Zelensky said Moscow’s combat power is at “maximum” strength in its push to capture the wider Donbas region, which includes Luhansk and Donetsk.

“Unfortunately, the front line is dividing the city in half, but the city is still defending itself; the city is still Ukrainian,” Aleksandr Stryuk, head of the civil-military administration in Severodonetsk, told a Ukrainian television channel. He called on residents to remain in hiding as the city comes under heavy air and artillery attacks, and he said there were enough reserves of humanitarian supplies to last “a few days.”

Stryuk said the casualty toll is not yet clear and that mobile connections in the city are unstable. “Evacuation is halted for now. Unfortunately, it is not possible because of the fighting,” he added.

Radio Svoboda quoted another official in the wider Severodonetsk district, Roman Vlasenko, as saying said that Russian forces had advanced into about half the city. Fighting was raging in the center, he said.

Russian troops have been fighting to make gains in Ukraine’s eastern Donbas region, which includes the Donetsk and Luhansk provinces, where separatist forces that have long controlled breakaway enclaves are fighting alongside Moscow’s troops to expand their grip.

Children walk among buildings destroyed during fighting in Mariupol, in territory under the government of the Donetsk People’s Republic in eastern Ukraine on Wednesday. Associated Press

Russia must capture the Ukrainian city of Kramatorsk and a key road linking the cities of Dnipro and Donetsk to achieve its probable goal of seizing the entirety of the eastern Ukrainian provinces of Luhansk and Donetsk, the British Defense Ministry said in an intelligence update Tuesday.

Russian forces appear to be seeking to encircle Ukrainians defending Severodonetsk, one of the last major Ukrainian cities in Luhansk that remains under Kyiv’s control, the ministry said. Progress by Russian forces has been slow, but gains are being held, it added. Severodonetsk is about 45 miles northeast of Kramatorsk.

Luhansk’s regional governor said last week that Ukrainian forces in Severodonetsk may have to retreat to avoid being fully surrounded. The city is already besieged on three fronts.

A Ukrainian court found two Russian soldiers guilty of shelling civilian sites during fighting in Kharkiv and sentenced them Tuesday to 11 1/2 years in prison. It was the second verdict handed down in a war crimes trial in Ukraine since the conflict began. Ukrainian prosecutor general Iryna Venediktova announced at a news conference Tuesday that Estonia, Latvia and Slovakia will join a joint effort by several eastern European countries and the International Criminal Court to investigate alleged war crimes in Ukraine.

The European Union announced late Monday its long-awaited deal to curtail use of Russian oil, a move it said would cut some 90 percent of oil imports from Russia by the end of this year. The agreement is softened by an exemption for pipeline oil, a concession to landlocked E.U. members, notably Hungary.

Also Tuesday:

– Zelensky sent his condolences to the family of French journalist Frédéric Leclerc-Imhoff, who was killed in eastern Ukraine when a Russian strike hit an armored evacuation truck he was traveling in.

– Zelensky has denounced Russia’s blockade on Ukrainian ports for halting the export of 22 million tons of grain. He accused the Kremlin of using African and Asian countries as “bargaining chips.” Turkish President Recep Tayyip Erdogan has stressed the need to establish a safe passage for sea exports of grain.