KYIV, Ukraine — Ukraine’s military on Monday barred aid workers and civilians from entering Bakhmut, saying it was too perilous as Russian forces tightened their grip, in what could be a prelude to a Ukrainian withdrawal and the biggest tactical gain for the deeply troubled Russian invasion since July.
But Ukraine’s military said it still held the besieged eastern city, though the one remaining major road it can use to deliver troops and supplies, or evacuate the wounded, was under Russian fire.
“Bakhmut is the epicenter of the enemy’s attack and therefore the situation is critical,” Col. Serhiy Cherevaty, the spokesman for Ukraine’s eastern military command, said in an interview on Monday.
He said that Ukrainian troops had repelled 19 assaults on Bakhmut over the previous 24 hours, but that no watershed moment had been reached. The city, he said, “is under Ukrainian control.”
Bakhmut lies at the heart of a brutal, monthslong battle. After leveling much of the city with artillery, the Russians now appear to have surrounded it on three sides, and to have captured several towns and villages around it. Ukraine’s military said on Monday that street fighting had also begun in two of Bakhmut’s neighborhoods.
For months, volunteers from Ukraine and abroad had taken extraordinary risks to evacuate civilians and provide medical care in Bakhmut, operating three heating and aid shelters in a city that has mostly lacked electricity or heat. (Pete Reed, an American volunteer medic, was killed in Bakhmut this month.) The presence of aid workers in this crucible of violence, despite the grave risks, had helped reassure the remaining residents that Ukraine had not abandoned them.
“We are fighting for people’s hearts,” one volunteer, Mykhailo Puryshev, said in a telephone interview. He estimated that 3,000 to 4,000 civilians were still in Bakhmut, including 60 children.
The Kremlin has focused on Bakhmut — which had a prewar population of about 70,000 and where several highways and rail lines converge — as pivotal to President Vladimir V. Putin’s stated goal of conquering Donbas, the vital industrial and mining region that makes up easternmost Ukraine.
Russia has poured enormous numbers of troops into trying to conquer it, driving conscripts into near-suicidal assaults in a bid to overwhelm Ukrainian defensive lines.
The city now lies in ruins, and the vast majority of its people have long fled, but Ukrainians have made Bakhmut a symbol of tenacious resistance and a rallying cry, and President Volodymyr Zelensky of Ukraine has rejected talk of giving it up. Ukrainian forces have also used Russia’s relentless wave of attacks as an opportunity to inflict thousands of casualties.
The result, military analysts say, has been slaughter out of proportion to the city’s strategic importance. U.S. officials estimate that Russia has seen nearly 200,000 fighters killed or wounded since it invaded almost a year ago, a staggering loss swelled by the battle for Bakhmut. But the Kremlin, undaunted, drafted about 300,000 men last fall and sent many of them to the Donbas.
In July, the industrial city of Lysychansk, on a rise overlooking the Siversky Donets River, fell to Russian control. It had held out for a week after Russia seized Sievierodonetsk, its twin city across the river.
As the Feb. 24 anniversary of the invasion approaches, Western analysts see the fight for Bakhmut and the surrounding area as a prelude to, or the early stages of, a broader new Russian offensive. Ukraine, hoping to fend off that assault and mount an offensive of its own, has been pleading with the West for more powerful and modern weapons, and faster delivery of arms.
The Ukraine Defense Contact Group, the U.S.-led coalition of some 50 countries providing military aid to Ukraine, will meet on Tuesday in Brussels. Among the items to be discussed — if unlikely to meet approval any time soon — is Kyiv’s call for fighter jets.
Jens Stoltenberg, NATO’s secretary general, said the meeting would also address how to ramp up production of munitions like artillery shells, which Ukraine is using faster than Western manufacturers can make them.
“It is clear that we are in a race of logistics,” Mr. Stoltenberg said on Monday. “Key capabilities like ammunition, fuel and spare parts must reach Ukraine before Russia can seize the initiative on the battlefield. Speed will save lives.”
Ukrainian officials want to bring to bear promised Western tanks and long-range artillery, among other weapons, in time to affect the intense fighting for Bakhmut and Kreminna, a Russian-held town about 30 miles to the north, and to prevent the Russians from advancing on the larger cities of Kramatorsk and Slovyansk.
In an assessment of the battlefield on Monday, Rochan Consulting, an analytical group based in Poland, noted that Russia had encroached on Bakhmut from the north and the south in recent days, and said the city could fall as soon as this week.
As Russian radio broadcasts in the city predict its imminent fall, “many people sit in basements and are afraid to go out or let their children out” even to be evacuated, said Mr. Puryshev, the aid volunteer.
Speaking in a video address posted online, a Ukrainian commander who goes by the nickname Madyar said the ban on aid workers and groups entering Bakhmut was necessary because the fighting now “exposes to danger even volunteers who come here with good intentions to help.” The Ukrainian Army will now provide aid to those who need it, he said.
“Bakhmut was, is and remains Ukrainian,” he said.
The decision suggests that the Ukrainian military cannot secure even areas in the city that for months had been considered relatively safe, such as neighborhoods on the western bank of the Bakhmutka River that are farther from Russian artillery.
Russia’s Ministry of Defense said on Monday that its forces had taken the village of Krasna Gora, on the northern edge of Bakhmut. The statement, posted on the Telegram messaging app, came a day after the Wagner private military company, whose forces have helped lead Russia’s campaign to seize Bakhmut, said that its “assault units” had taken the village.
Bakhmut has been under Russian bombardment since last spring, but the fighting there has intensified since the fall, with the Russians firing thousands of artillery shells per day.
Wagner recruited mercenaries from among Russian inmates with the promise of pardons, using them on the front lines in Bakhmut, where they have suffered heavy casualties.
Moscow’s forces fought their way town by town, street by street, house by house toward the city, breaching multiple lines of defense. Now, they are sending small units that slip into the city, said Colonel Cherevaty, the Ukrainian military spokesman.
Steven Erlanger contributed reporting from Brussels, Maria Varenikova from Kyiv, Ukraine, and Richard Pérez-Peña from New York.