The better part of a Russian army battalion with up to a thousand troops tried to cross a pontoon bridge over the Siverskyi Donets River in recent days.
They were caught at the river bank. The rapid destruction of around three dozen tanks and other armored vehicles, along with the bridge itself, underscores Russia's deeper troubles as it tries to make gains in eastern Ukraine.
An unnamed U.S. Defense Department official told reporters on Tuesday that the Russian ground force in the Donbas is slow. The Russians can't cross rivers.
The Siverskyi Donets is one of several water barriers Russian battalions must cross in order to advance west into Ukrainian-held territory. According to the general staff of the Ukrainian armed forces, the battalion that got caught at the pontoon bridge was trying to strike at the city of 20,000 that lies 17 miles west of the doomed bridge.
The crossing was spotted by the Ukrainian army's 17th tank brigade, which uses small drones to look over the battlefield. The army has four active tank brigades. T-64 tanks are used by its line battalions. The brigade's howitzers got the first crack at the Russian bridge.
At least seven T-72 and T-80 tanks, 17 BMPs, seven MT-LB armored tractors, five other vehicles, and a tugboat were destroyed in the shelling.
It is unclear how many Russians died or were wounded, but it is worth noting that no battalion can lose three-quarters of its vehicles and remain capable of operations. The Ukrainians were removed from the battlefield in one strike.
Russian forces are trying to hold positions on the right bank after their defeat, according to the general staff in Kyiv. Russian forces are leaving the city of Kharkiv farther north.
It is dangerous to cross a water obstacle during war. The Russians have knocked out some Ukrainian spans, but the Ukrainians claim to have won the most.