KYIV, Ukraine — As Russia steps up its offensive in eastern Ukraine, weeks of failed attacks on a Ukrainian stronghold have left two Russian brigades in tatters, raised questions about Moscow’s military tactics and renewed doubts about its ability to maintain sustained, large-scale ground assaults.
The fighting has also come at a cost for Ukraine, which is expending vast amounts of ammunition to repel Russia’s growing numbers of ground troops, often supported by heavy armor, artillery and close air support. That has added urgency to Ukraine’s pleas for more ammunition, while Western allies this week expressed increasing concern about their ability to meet the demand.
The battle around the Ukrainian city of Vuhledar, which sits at the intersection of the eastern front in the Donetsk region and the southern front in the Zaporizhzhia region, is viewed as one of Moscow’s opening moves of a nascent spring offensive. Though it has been playing out for weeks, the scale of Russia’s losses is only beginning to come into focus.
Accounts from Ukrainian and Western officials, Ukrainian soldiers, captured Russian soldiers, Russian military bloggers, and video and satellite images all paint a picture of a faltering Russian campaign that continues to be plagued by dysfunction.
Moscow has rushed tens of thousands more troops, many of them inexperienced new recruits, to the front line in recent weeks as President Vladimir V. Putin’s forces seek to demonstrate progress before the anniversary of his full-scale invasion on Feb. 24.
In attempting to capture Vuhledar, which lies near a rail line Russia uses to supply its forces, “the enemy suffered critical losses,” Col. Oleksii Dmytrashkivskyi, a spokesman for Ukrainian military forces in the area, said in an interview.
The Russians failed to take into account the terrain — open fields laden with mines — or the strength of the Ukrainian forces, he said. Two of Russia’s most elite brigades — the 155th and 40th Naval Infantry Brigades — were decimated in Vuhledar, Colonel Dmytrashkivskyi said.
In one week alone, the Ukrainian General Staff, which is responsible for military strategy, estimated that Russia lost at least 130 armored vehicles, including 36 tanks. That estimate has been supported by accounts from Russian military bloggers, whose reporting on the war is influential in Russia, and by drone footage of the destruction reviewed by independent military analysts.
Ben Wallace, Britain’s defense secretary, on Wednesday cited reports that “a whole Russian brigade was effectively annihilated” in Vuhledar, where he said that Moscow “lost over 1,000 people in two days.” The British defense intelligence agency reported last week that Russian units had “likely suffered particularly heavy casualties around Vulhedar,” abandoning at least 30 armored after one failed assault.
Mr. Wallace told LBC News, a British news outlet, on Wednesday that the losses in Vuhledar showed the result of “a president and a Russian general staff that defies reality or ignores reality and simply doesn’t care how many people they are killing of their own, let alone of the people they are trying to oppress.”
Many of the captured soldiers were newly mobilized under a call-up Mr. Putin announced last September of some 300,000 recruits, while others had been recruited by the Wagner mercenary group, according to Ukrainian and Russian accounts.
In recent weeks, a rivalry between Wagner forces and the regular Russian army has opened up, with the mercenary group claiming that its fighters are more capable.
Wagner fighters have led the Russian campaign in the city of Bakhmut, 60 miles north of Vuhledar. Ukrainian forces defending the city are in an increasingly precarious position, but only after months of unrelenting Russian assaults that have come at a heavy cost for Moscow and left the city in ruins.
The Grey Zone, a Telegram channel that is affiliated with Wagner, was scathing about Russian military efforts in Vuhledar, and called for Russian commanders responsible for the losses to be held accountable in public trials.
“Impunity always breeds permissiveness,” a recent post said.
A Russian marine who survived the fight in Vuhledar told the Russian media outlet 7×7, which is based in the Komi region of Russia, that those who survived the battle were considered deserters. The marine, whose identity the news outlet did not disclose, citing the need to protect his safety, said he was part of the third company of the 155th brigade. After his unit’s failed assault, he said, only eight soldiers were left alive.
“It would have been better if I had been captured and never returned,” he said.
Moscow has continued to insist all is going according to plan. On Sunday, Mr. Putin of Russia said that the “marine infantry is working as it should. Right now. Fighting heroically.”
Natalia Yermakcontributed reporting.