Russia confirmed Wednesday night that Ukraine invaded the Kursk Oblast near the border, one of the most significant actions of Ukraine on Russian soil since the Russian invasion in February 2022.
Following the invasion, Alexei Smirnov, governor of the region, declared a state of emergency.
The Ukrainian attack is believed to be a result of the Russian army's decision to intensify attacks in recent periods, which helped Moscow advance in the conquest of Ukraine - albeit at a slow pace.
The battles are mainly taking place in the area of the town of Sudzha, located 530 kilometers from Moscow and constituting an important center for the transportation of natural gas.
Ukraine has not commented on the attack. Russian estimates indicate around 1,000 soldiers are involved.
The Russian Chief of Staff claimed that the Russian Army managed to halt the continued advance of Ukrainian forces.
If the battles continue, it might force Russia to transfer forces from the combat zone in Ukraine in order to protect the interior within Russia.
The attack occurs as Western countries supporting Ukraine want to ensure that no Western-made weaponry is used to attack Russian territory.
The White House spokeswoman said that the US is waiting for clarifications from Ukraine on the matter and added that the US has no additional information on the matter.
Russian President Vladimir Putin condemned the attack and said, "The Kyiv regime has launched another major provocation." He also claimed that Ukraine is carrying out "indiscriminate shooting using different types of weapons, including missiles on civilian structures."