What’s behind Ukraine’s surprise incursion into Russia’s Kursk region?

Ukrainian soldiers have entered western Russia in a move that has bewildered Moscow, successfully tested its weak border defences and may deal a blow to its natural gas supplies to Europe.

Kyiv dispatched hundreds of servicemen backed by armoured vehicles, artillery and drones to the Kursk region on Tuesday, according to Russian officials, Ukrainian servicemen and media reports.

The raid follows several incursions by Russian nationals fighting for Ukraine who briefly raided Kursk and neighbouring Belgorod in 2023 and heavy Ukrainian shelling of Belgorod this year.

On Tuesday morning, Ukrainian forces fought through the border and approached Sudzha, a sleepy town of 5,000 people whose central square is still dominated by a statue of Soviet Union founder Vladimir Lenin.

But Sudzha is important as the location of the only pumping station that delivers Russian natural gas to Europe via Ukraine.

Despite the war, Ukraine still rents its Soviet-era gas pipeline to Russia’s gas monopoly, Gazprom, for $2bn a year.

The transit deal expires in January – if the raid doesn’t stop it now.

Because of the attack, “there is a risk of a pause of [Russia’s] natural gas supplies to the European Union via our transit system,” Kyiv-based analyst Aleksey Kushch told Al Jazeera.

The Kursk nuclear power station, one of the world’s oldest, is located in the town of Kurchatov, about 70km (40 miles) east of Sudzha.

Ukrainian drones have been spotted in Kurchatov, and some analysts said Kyiv wants to destabilise the Russian energy system the way Moscow has targeted Ukrainian power stations and its energy grid.“The main thing [about the attack] is energy supplies. The more destabilised they are, the more destabilised the Russian economy is,” Kyiv-based analyst Taras Zahorodniy said in televised remarks.

By Wednesday afternoon, Ukrainians surrounded Sudzha, seized three villages and were spotted near 10 more, Russian officials and media reported.

“In the past 24 hours, our region has been heroically countering the attacks of Ukrainian Nazis,” Kursk acting Governor Aleksey Smirnov wrote on Telegram on Wednesday, repeating the Kremlin’s narratives about the “Nazi junta” in Kyiv.

At least three civilians – two drivers and a woman – have been killed, and 24 have been wounded, including six children, according to Smirnov and health officials.

The governor urged locals to donate blood for the wounded and said “the situation is controllable”.

But even the dry, legalese tone of the Kremlin’s statements cannot hide the gravity of the situation.