Ukrainian officials acknowledged Friday that Russian forces had taken more than three dozen small towns in their initial drive this week to seize eastern Ukraine, offering the first glimpse of what promises to be a grinding brawl by the Kremlin to achieve broader territorial gains in a new phase of the two-month-old war.
The fighting in the east — along increasingly fortified lines that stretch across more than 300 miles — intensified as a Russian commander signaled even wider ambitions, warning that the Kremlin’s forces aimed to take “full control” of southern Ukraine all the way to Moldova, Ukraine’s southwest neighbor.
While it seemed unlikely that the commander, Gen. Rustam Minnekayev, would have misspoken, his warning still drew skepticism, based on Russia’s probable difficulty in starting another broad offensive and the general’s relatively obscure role in the hierarchy. But his threat could not be ruled out.
The broader war aims that he outlined at a defense industry meeting in a Russian city more than 1,000 miles away from the fighting would be far more ambitious than the downscaled goals set out by President Vladimir V. Putin in recent weeks, which have focused on gaining control of the Donbas region of eastern Ukraine.
Some political and military experts suggested the general’s statement could have been part of Russia’s continuing efforts to distract or confuse Ukraine and its allies. General Minnekayev’s official job involves political propaganda work and does not typically cover military strategy.
On Friday, fierce fighting was underway across a band of southeastern Ukraine, engulfing communities on the banks of the Dnipro River. While Ukrainian officials acknowledged that Russia had taken control of 42 small towns and villages in recent days, they said those same places could be back in Ukrainian hands before long.
Western analysts said Russia’s forces, in both the slow but largely successful fight for the southern city of Mariupol and the unsuccessful battle for Kyiv, had been battered and weakened. But rather than resting, reinforcing and re-equipping the forces, Moscow is pressing forward in the east.
The Russian military appears to be trying to secure battlefield gains — including capturing all of the Donetsk and Luhansk regions, or oblasts — ahead of May 9, when Moscow holds its annual celebration of its World War II victory.
“They’re not taking the pause that would be necessary to re-cohere these forces, to take the week or two to stop, and prepare for a wider offensive,” said Mason Clark, an analyst at the Institute for the Study of War in Washington. “They’ll likely be able to take some territory. We do not think they’re going to able to capture the entirety of the oblasts in the next three weeks.”
In his remarks on Friday, General Minnekayev asserted that one of Russia’s goals was “full control of the Donbas and southern Ukraine.”
He said that would allow Russia to control Ukraine’s Black Sea ports, “through which agricultural and metallurgical products are delivered” to other countries. Still, despite repeated attacks, Russia has failed to seize those ports, including Odesa, a fortified city of 1 million people.
“I want to remind you that many Kremlin plans have been destroyed by our army and people,” Andriy Yermak, chief of staff to Ukraine’s president, Volodymyr Zelensky, wrote on social media in response to General Minnekayev’s remarks.
General Minnekayev also issued a veiled warning to Moldova, where Moscow-backed separatists seized control of a 250-mile sliver of land known as Transnistria in 1992.
“Control over the south of Ukraine is another connection to Transnistria, where there is also evidence of oppression of the Russian-speaking population,” the general said, echoing false claims of a “genocide” against Russian speakers in eastern Ukraine that Mr. Putin used to help justify the Feb. 24 invasion.
Transnistria has never been recognized internationally — not even by Russia. But Russia keeps 1,500 soldiers there, nominally to keep the peace and guard a large Soviet-era munitions cache.
Moldova had no immediate response to the general’s statement. A poor country of 2.6 million, Moldova is considered vulnerable to further Russian incursions. It is not a member of NATO or the European Union, but it hastily applied for E.U. membership last month.
Yuri Fyodorov, a Russian military analyst, said that the broader aims detailed by General Minnekayev “from the military standpoint are unreachable.”
“All of Russia’s combat-ready units are now concentrated in the Donbas, where Russia failed to achieve any significant advances over the past five days,” Mr. Fyodorov said in an interview. General Minnekayev’s rank, he said, would generally not allow him to make such sweeping policy statements that also contradict what has been said by the country’s top leaders.
Dmitri S. Peskov, the Kremlin’s spokesman, declined to comment on General Minnekayev’s remarks.
As Western allies race to arm Ukraine with increasingly heavy, long-range weapons, Prime Minister Boris Johnson of Britain, on a visit to India on Friday, said his country was considering sending tanks to Poland so that Warsaw could then send its own tanks to Ukraine. The Biden administration said this month that it would also help transfer Soviet-made tanks to Ukraine.
The Russian Defense Ministry, in its first statement on casualties from the April 14 sinking of the Moskva, the flagship of Russia’s Black Sea fleet, said that one crew member had died, 27 were missing and 396 had been evacuated. Relatives of at least 10 Moskva crew members had voiced frustration over the Kremlin’s silence, which was turning into a test of its strong grip on information that Russians receive about the war.
Ukraine said it had sunk the Moskva with two missiles — an assertion corroborated by U.S. officials — while Russia claimed that an onboard fire had caused a munitions explosion that doomed the ship.
As Russia hardened its crackdown on any domestic opposition to the war, it opened a criminal case against Vladimir Kara-Murza, a Russian pro-democracy activist and a contributing columnist for The Washington Post, for spreading “false information,” his lawyer said Friday.
Mr. Kara-Murza, 40, arrested earlier this month, faces 10 years in prison, according to the official decree against him posted online by his lawyer, Vadim Prokhorov.
It said he was being investigated for remarks he had made before Arizona lawmakers on March 15. Mr. Kara-Murza told a local news outlet in Phoenix that month that Russia was committing “war crimes” in Ukraine but that “Russia and the Putin regime are not one and the same.”
“Americans should be infuriated by Putin’s escalating campaign to silence Kara-Murza,” Fred Ryan, the publisher of The Post, said in a statement.
Mr. Putin, who has become increasingly vilified in the West over the war, has not completely rejected diplomatic engagement. On Friday, he agreed to meet with the United Nations secretary general, António Guterres, in Moscow next week, a stark change from his refusal to even take Mr. Guterres’s phone calls. Still, the meeting did not signal a softening of Mr. Putin’s views on Ukraine, a former Soviet republic that he has said should not even be a sovereign country.
Ukraine’s government said the fighting had made it too dangerous to organize any evacuations from a war that Michelle Bachelet, the United Nations High Commissioner for Human Rights, called a “horror story of violations perpetrated against civilians.”
After another attack on the northeastern city of Kharkiv on Friday, residents watched as smoke rose over shops. In the ruined port of Mariupol, hundreds of civilians and the last organized Ukrainian fighters remained trapped in a sprawling steel plant, issuing urgent pleas for help from underground bunkers. Newly released satellite images of the city showed hundreds of hastily dug graves, lending credibility to Ukrainian claims that Russia was trying to cover up atrocities.
And in the Zaporizhzhya region of south-central Ukraine, Ukrainian troops were dug in about two miles from Russian forces that were trying to push north in an effort to fortify a land bridge connecting Russian territory with the Crimean Peninsula, which Mr. Putin annexed in 2014.
The Ukrainian army’s 128th Separate Mountain Assault brigade, armed with anti-tank missiles provided by the Americans and the British as well as other advanced weapons systems, claimed to have destroyed two Russian T-72 tanks that had strayed too close to its positions.
“We are on our own land,” Captain Vitaliy Nevinsky, the brigade’s commander, said. “We are defending ourselves and knocking out this horde, this invasion of our territory.”
Anton Troianovski reported from Hamburg, Germany, Ivan Nechepurenko from Tbilisi, Georgia, and Michael Levenson from New York. Reporting was contributed by Marc Santora from Krakow, Poland, Michael Schwirtz from Zaporizhzhya, Ukraine, Tyler Hicks from Kharkiv, Ukraine, Nick Cumming-Bruce from Geneva, Julian E. Barnes from Washington, Farnaz Fassihi from New York and Sameer Yasir from New Delhi.