Russian officials said Wednesday they were fighting off Ukrainian cross-border raids in a southwestern province for a second day, as Kyiv officials remained quiet about the scope of the operation.

Russian President Vladimir Putin described the incursion into the south-western Kursk region as a “large-scale provocation” and said he will hold a meeting with top defense and security officials to discuss the situation.

“The Kyiv regime has undertaken another large-scale provocation and launched indiscriminate shelling of civilian buildings, residential houses, ambulances with different types of weapons,” Putin said at a meeting with Cabinet officials. He instructed the Cabinet to coordinate assistance to the Kursk region.

The head of the region urged residents to donate blood due to the intense fighting.

“In the last 24 hours, our region has been heroically resisting attacks” by Ukrainian fighters, acting Gov. Alexei Smirnov said on Telegram, adding that all emergency services were on high alert.

If confirmed, the reported battalion-sized cross-border foray would be among Ukraine’s largest since Russia’s full-scale invasion, and unprecedented for its deployment of Ukrainian military units. Kyiv’s aim could be to draw Russian reserves to the area, potentially weakening Moscow’s offensive operations in several parts of Ukraine’s eastern Donetsk region where Russian forces have increased attacks and are advancing gradually toward operationally significant gains.

But it could risk stretching outmanned Ukrainian troops further along the front line, which is more than 620 miles long. Even if Russia were to commit reserves to stabilize the new front, given its vast manpower and the relatively small number of Ukrainian forces engaged in the operation, it would likely have little long-term impact.

However, the operation could boost Ukrainian morale at a time when Kyiv’s forces are facing relentless Russian attacks and are expected to face more challenges in coming weeks.

Several Ukrainian brigades stationed along the border region said they could not comment. Ukraine’s Defense Ministry and General Staff also said they would not comment.

Russian forces have swiftly repelled previous cross-border incursions, but not before they caused damage and embarrassed authorities.

The Russian Defense Ministry said Tuesday that up to 300 Ukrainian troops, supported by 11 tanks and more than 20 armored combat vehicles, had crossed into Russia and suffered heavy losses.

It said Wednesday that military and border guard troops “continued to destroy Ukrainian military units in the areas alongside the border in the Kursk region.”

The ministry said Russian forces backed by artillery and warplanes “didn’t allow the enemy to advance deeper into the territory of the Russian Federation.”

It wasn’t possible to verify the Russian claims.

Open-source monitors have also not been able to verify the claims. The U.S.-based Institute for the Study of War could not verify whether damaged and abandoned armored vehicles shown in geolocated video 4 miles north of the border west of Lyubimovka in the Kursk region were Ukrainian.

The think tank also cast doubt on video shared by Russian military bloggers claiming to show the aftermath of the Ukrainian raids. Most of the damage shown “appears to be the result of routine Ukrainian shelling and does not indicate that there was ground activity in the area,” it said in its daily report.

Responsibility for previous incursions into Russia’s Belgorod and Bryansk regions has been claimed by two murky groups: the Russian Volunteer Corps and the Freedom of Russia Legion, which are made up of Russian citizens and have fought alongside Ukrainian forces.

Disinformation and propaganda have played a central role in the war, now in its third year.

Some Russian war bloggers who have proved knowledgeable about the war said that Ukrainian soldiers were in Kursk.

Rybar, a Telegram channel run by Mikhail Zvinchuk, a retired Russian Defense Ministry press officer, said Ukrainian troops had seized three settlements in the region and continued to fight their way deeper into it.

Another pro-Kremlin military blog, Two Majors, claimed that Ukrainian troops had advanced up to 9 miles into the region.

Neither claim could be independently verified.

The Kursk region’s border with Ukraine is 150 miles long, making it possible for saboteur groups to launch swift incursions and capture some ground before Russia deploys reinforcements.

George Barros, of the Institute for the Study of War, recently told CBS News that Russia is using new tactics — including soldiers on motorcycles — to seize 430 square miles of territory over the past nine months.

But the price Russia is paying to make these advances is very high. According to Barros, the Russians are losing between 25,000 to 30,000 troops per month. By some estimates, Russia has suffered a staggering half-million killed or wounded since the invasion began.

Last week, Ukraine said it had received the bodies of 250 killed soldiers in one of the largest exchanges of remains since Russia invaded.