Ukrainian forces launched a surprise offensive in Russia’s Kursk region on Sunday, apparently in an attempt to regain the initiative on the battlefield ahead of Donald Trump’s impending return to the White House.

The video showed Ukrainian tank columns advancing across snowy fields toward the village of Bolshoe Schlachtskoe, northeast of the Ukrainian-held Russian town of Sudzha. Vehicles could also be seen driving through empty rural settlements.

Ukrainian officials confirmed that a large-scale operation was taking place. Russian military bloggers reported heavy fighting. According to the Ukrainian General Staff, there were 42 battles in the Kursk region on Sunday, 12 of which were still ongoing.

There were unconfirmed reports that Ukrainian troops had entered the Russian villages of Berdin and Novosotnitskii. Ukrainian sappers cleared mines overnight. Extensive electronic countermeasures were used to disable some Russian drones.

Ukraine launched a significant cross-border attack on the Kursk region almost six months ago. It was the first time enemy tanks had penetrated Russian territory since World War II and represented a major embarrassment for the Kremlin.

Since then, the Russian army has been trying to drive out the Ukrainian forces. It had some successes – recapturing about 40% of the lost territory – but was unable to completely displace them.

Andriy Yermak, President Volodymyr Zelensky’s office chief, said Ukraine’s latest attack was successful. “Kursk region, good news, Russia gets what it deserves,” he wrote on Sunday.

Andriy Kovalenko, a senior official at Ukraine’s National Security and Defense Council, confirmed the operation on Sunday. “In the Kursk region, Russians are deeply concerned. They were attacked on multiple fronts, which came as a surprise to them,” he posted on Telegram.

Russian military bloggers speculated that Ukraine was trying to capture the Kursk nuclear power plant in the city of Kurchatov. Kyiv has previously rejected this. The power plant is located far from the existing front line.

Sunday’s operation comes ahead of Donald Trump’s return as US president on January 20 and possible “peace negotiations” later this year. Zelensky has suggested that the land around Kursk could play a role in any peace agreement. Kyiv currently controls 585 square kilometers of Russian territory.

Moscow has shown little sign that it is ready to stop fighting. Putin said his territorial claims remained unchanged. These include four Ukrainian regions that he “annexed” in 2022, including the cities of Zaporizhzhia and Kherson, as well as other areas that Russia does not control.

Putin’s apparent calculation is that the new US administration will cut off all military supplies to Ukraine, allowing Russian forces to make further gains in 2025.

Within Ukraine, Russia is already advancing at its fastest pace since its full-scale invasion in 2022. Russian troops try to flank the Ukrainian city of Pokrovsk in Donetsk Oblast. In the last two days they captured several remote villages in the southwest.

The last Ukrainian defenders were recently forced to abandon their underground fortress at a thermal power plant in the eastern city of Kurakhove. Since then, the Russians have captured the destroyed complex and fighting has broken out on the outskirts of Kurakhove.

The recent raid on Kursk was made possible by the freezing weather, which made it easier for Ukrainian armored units to advance. U.S.-supplied Bradley Fighting Vehicles were reportedly used to carry Ukrainian infantry to forward positions below a tree line.

There was some criticism of Ukraine’s counteroffensive in Russia at a time when exhausted Ukrainian troops were struggling elsewhere. The Commander-in-Chief of Ukraine, Colonel Oleksandr Syrskyi, defended its tactics and visited the Kursk sector last week.

Syrskyj said the operation forced Russia to maintain a large group of troops on its own territory and transfer reserves from other directions. He claimed Moscow lost 38,000 people – killed or injured – and more than a thousand pieces of equipment.

Since August, 700 Russian soldiers and a handful of officers from the FSB secret service have been captured in and around Kursk. This has allowed Ukraine to repatriate its own prisoners of war, including 189 who were brought back just before the New Year, Syrskyi said.

On Saturday, Zelensky said Russia had lost up to a battalion of North Korean soldiers deployed to the battle for Kursk Oblast in just two days. They were wiped out along with Russian paratroopers in the village of Makhnovka, he said.

North Korean battle groups were reportedly sent to several frontline villages southeast of Sudzha. According to Zelensky, more than 3,000 people have been killed or injured so far.