Within about a day, Ukrainian forces broke through two defense lines in Russia’s Kursk region that Moscow had built over two and a half years at a cost of 15 billion rubles (about $109 million), Russian publication Agenstvo reported.

According to Agentsvo, the fortifications were built by the Russian Defense Ministry and the Border Service of the Federal Security Service (FSB).

Open source intelligence (OSINT) analyst Brady Afrik, who created a map of Russian defenses using satellite imagery, identified two defense lines in the Korenevsky and Sudzhansky districts of the Kursk region – one along the border and another 5-10 kilometers away from it.

Agentsvo suspects that the lack of troops could be the reason for the rapid fall of the fortifications.

In September 2023, the Ukrainian Center for National Resistance (CNR) released aerial photographs showing a shortage of troops and equipment at many positions in the Kursk region, as most forces had been relocated to Donetsk and Zaporizhia.

According to an anonymous source from the Ukrainian General Staff quoted in the Economist, during the Kursk Offensive, Kiev selected some of its most powerful units to attack the weakest point on the Russian border.

The 80th Air Assault Brigade, one of Ukraine’s best-equipped and fastest units, is reportedly involved in the ongoing invasion of the Kursk region of Russia.

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Combat zone in the Kursk region increased by 70 square kilometers in one day

The entire combat area now covers 720 square kilometers. The Russian Defense Ministry is now publishing old videos claiming that these are new “successful attacks.”

Kiev has not yet revealed the exact objectives of the Kursk operation, but if one goal was to pull Russian troops away from the more difficult sections of the front, the results are mixed. Russian advances in the most difficult areas, such as the Donbass, continue, although some enemy units have been moved from Kharkiv to Kursk.

“Their commanders are not idiots,” says the source from the Ukrainian General Staff. “They are moving troops, but not as fast as we would like. They know that we cannot extend logistics by 80 or 100 km (50 or 62 miles).”

A video circulating on social media shows a T-64BV or T-80BV tank, a UR-77 mine-clearing vehicle, an IMR-2 engineer vehicle, Soviet BTR-80s and American Stryker rifles, most of which are equipped with anti-drone frames, driving past a Ukrainian mortar team. The 80th Air Assault Brigade is the only unit in Ukraine with such a mix of ex-Soviet and American equipment, suggesting its presence in the Kursk operation.

Ukraine’s invasion of Russia’s Kursk coast on August 6 is Kyiv’s largest cross-border operation since Moscow began its invasion of Ukraine more than two years ago.

The attack, which displaced tens of thousands of people, was the most significant attack by a foreign army on Russian territory since World War II.

A senior Ukrainian official told AFP that the operation was aimed at dispersing Moscow’s troops and destabilising the country after months of slow Russian advances along the front line.

The Kremlin was apparently completely surprised by the attack and the Moscow army sent reserve troops, tanks, aircraft, artillery and drones into action to quell the attack.