Ukrainian soldiers have released dramatic footage of tanks smashing through Russia’s £90 billion fortifications in Belgorod, mocking Kremlin claims that the region’s borders were impenetrable. The video, posted by the 225th Separate Assault Regiment on Telegram, shows armoured vehicles advancing over several lines of defences in the western part of Belgorod Oblast, close to the Ukrainian border.

A message accompanying the clip said: “After our operation in Kursk, the Russians ‘drew conclusions’: they reinforced all borders to prevent another breakthrough elsewhere. Over RUB 10 billion (about US$115.8 million) were spent in Belgorod Oblast on ‘modern and reliable fortifications’… What’s with your faces, Russians?” At current exchange rates, 10 billion rubles is worth close to £90 million, with the footage apparently underscoring the scale of Russia’s failed investment in the area.

The footage also corroborates Kyiv's claims that its forces are now operating on Russian territory, which President Volodymyr Zelenskyy has described as a necessary act of self-defence.

Earlier this week, Mr Zelenskyy confirmed for the first time that Ukrainian troops were active inside Belgorod Oblast, describing the operations as a justified response to the Russian invasion.

Speaking on April 8, he said: “They are fighting on the border with the Russian Federation, and that is a fact. We have no other way out, because they are shelling our border villages.

“They must know that if they go further, we will respond accordingly.”

The confirmation followed reports by Russia’s Defence Ministry on March 18 that Ukrainian troops had attempted a breakthrough near the settlements of Demidovka and Prilesye, prompting speculation about the extent of Ukraine’s operations across the border.

When presseed about those reports at the time, Mr Zelensky said Ukraine had the right to take preemptive steps to stop Russian attacks. He did not confirm Ukrainian troop movements inside Russia but said Kyiv would do whatever was necessary to prevent further aggression.

Russia responded by funnelling billions of rubles into reinforcing its border zones, particularly in Belgorod and Kursk.

Satellite images released earlier this year showed vast networks of trenches, concrete blocks, and so-called ‘dragon’s teeth’ stretching for miles—intended to stop or slow down any Ukrainian advance.

The defences dubbed the Surovikin Line after a Russian general, have become a symbol of the Kremlin’s determination to keep Ukrainian troops out of its territory. But the latest video calls their effectiveness into question.

By breaching multiple layers of what was supposed to be a heavily fortified zone, Ukraine has not only demonstrated tactical mobility but also inflicted a propaganda blow on Moscow.

There was no immediate comment from the Russian Defence Ministry on the footage.

Mr Zelensky has consistently insisted that operations beyond Ukraine’s borders are aimed at safeguarding lives, critical infrastructure and military advantage.