Four days after the Ukrainian offensive began, Russia has declared the situation in the Kursk region as an emergency on a "federal level", writes AP.
And in nearby Lipetsk, evacuation is being ordered after a drone attack. A fire is also reported to have broken out at an airbase in the region, according to state-run Russian news agencies.
In a post on the messaging app Telegram, Ukraine's general staff writes that it attacked the airbase on Thursday and struck at warehouses with aerial bombs, reports AFP.
The city of Lipetsk is located about 33 miles from the Ukrainian border and near the Kursk region. The counteroffensive is likely the largest on Russian soil since Russia's full-scale invasion of Ukraine in 2022.
Deployment of soldiers
Russian state media report that Russia is deploying soldiers to Kursk.
Russia's Defense Ministry says on Friday that it "continues to repel attempts to intrude into the territory of the Russian Federation by the Ukrainian armed forces".
On the Ukrainian side of the border in the Kursk area, 20,000 people are being urged to evacuate, according to Ukrainian police.
"New front"
According to the American think tank ISW (Institute for the Study of War), Ukrainian forces have "broken through at least two Russian defense lines" and captured over ten communities since the offensive began on Tuesday. Fighting is also ongoing in the air. ISW also assesses that Ukrainian forces have advanced more than three miles into Russia on Thursday, based on geolocated images and Russian bloggers.
Military expert Joakim Paasikivi believes that the attacks on Russian territory could mean a turning point in the war.
This is a completely new dynamic. This could very well be a new front, he says.
Russia's President Vladimir Putin has called the offensive a "large-scale provocation".
