RT reported that the night attack targeted a location in Sumy province (Ukraine), which played an essential role in Kiev's logistics in the attack on Kursk province in Russia.
The Russian airstrike destroyed a Ukrainian command facility in Sumy province, the Russian Defense Ministry said, releasing a video of the night attack.
The airstrike took place in the early morning of August 20, the Russian military said. A Russian Su-34 hypersonic aircraft dropped a bomb on a target identified by the Russian Defense Ministry as being operated by the 47th Mechanical Brigade of the Ukrainian ground force.
The video taken from above does not show the city's dark landscape with an intersection, believed to be in the heart of Glukhov city, about 15 km from the Russian border.
A massive explosion broke out in one of the buildings, marked a auto repair shop on Google Maps. A secondary explosion occurred shortly thereafter.
The Russian military said the site was being used by the 47th Mechanized Brigade as a command post and ammunition depot. Ukrainian soldiers, including commanding officers, were killed in the attack.
The Russian Defense Ministry did not estimate the number of casualties in Ukraine, but media reports said that up to 90 soldiers were killed, including 30 people of higher rank than regular soldiers.
Sumy region borders Russia's Kursk region, where Ukraine is holding territory in an offensive launched two weeks ago.
One of the goals of the attack, as declared by Ukrainian President Volodymyr Zelensky, was to establish a " buffer zone" to prevent cross-border attacks by Russia.
Moscow has called the attack a terrorist attack, claiming that Kiev had deliberately targeted civilians.
The Russian military estimated Ukrainian losses in the attack at 3,800 people as of August 19.
According to the Russian military, the attack also cost Kiev hundreds of tanks and other heavy weapons, many of which were supplied by Western sponsors.
