Russia’s Defense Ministry says it has repelled a major offensive by Ukraine in Donetsk, saying it killed 250 troops and destroyed armored vehicles.
The video, which Russia says is a war, appears to show military vehicles entering fields under heavy fire.
But there was no comment from Kiev and Russia’s claim has not been independently verified.
Kyiv says the Ukrainian counteroffensive is long-awaited, but its launch cannot be forewarned.
It is not clear whether the alleged attacks indicate that a new push to retake Ukrainian land from Russian forces has begun in earnest.
Ukraine launched a “large-scale offensive” using six mechanized and two tank battalions in the Donetsk region on Sunday, the Russian Defense Ministry said.
The Ukrainians tried to break through Russian defenses, which Kiev saw as the most vulnerable part of the front, but it “did not achieve its tasks, it did not succeed,” it said.
Moscow said Ukraine lost 250 troops and 16 tanks.
Ukraine has been planning a counterattack for months. But it wanted as much time as possible to train troops and acquire military equipment from Western allies.
Officials in Kiev have warned against public speculation about the attack, saying it could help the enemy.
In a video posted on Sunday’s Telegram, the Defense Ministry said, “The projects want peace. There will be no announcements at the start.
Footage showed masked and armed troops holding their fingers to their lips.
The government in Kiev has much at stake as it must show the people of Ukraine — and its Western allies — that it can break through Russian lines, end the effective military stalemate, and recapture some of its sovereign territory.
On Monday morning, the commander of Ukraine’s ground forces, Oleksandr Chirsky, said troops were “moving forward” towards Bagmut and had destroyed Russian positions near the city.
The claim was made by the Liberty of Russia Legion (FRL), which described the announcement as a joint statement with the Russian Volunteer Corps (RDK).
Both groups want to topple President Vladimir Putin. They oppose the full-scale invasion of Ukraine that he launched in February last year.
Belgorod’s top official, Vyacheslav Klatkov, said the soldiers had agreed to meet their captors if they were alive. But the militants later said that the governor did not have the courage to meet them and that they would hand over the captives to Ukraine.
Russia has blamed Ukraine for recent attacks on its border areas, but Kiev has not been directly contacted.
An energy plant caught fire following a drone attack on Monday morning, officials in Belgorod said.
Governor Vladislav Shabsha said two drones fell on a major road in Russia’s Kaluga region – bordering southern districts around Moscow. Mr Shabsha said there was no explosion and the area was now cordoned off.
There is no independent confirmation of any attack, but Moscow says the Belgorod region is a regular target for drone strikes from Ukraine.