KYIV — Ukrainian forces are expanding their cross-border incursion to a new Russian border region, while Moscow is racing reinforcements to the area to repel the largest attack on Russian soil since the start of the war. 

Ukraine has also reportedly captured a key strategic target that could help Kyiv in the event of future peace negotiations with Moscow — a major gas pipeline hub — while Russia is scrambling to defend a nearby nuclear power plant that also could be in Ukraine’s sights.

Ukrainian forces published a video Saturday at the Russian village of Poroz in the Belgorod region with their soldiers holding a Ukrainian flag. 

Meanwhile Russia has declared a “Counter-Terrorism Operation” in three regions — Kursk, Belgorod, and Bryansk — as Ukraine troops make gains. The Russian protocol involves vehicle checks, monitoring phone calls, and tighter security. 

The Russian government previously imposed similar measures at Moscow during the short-lived Wagner-group rebellion in June 2023. 

The Russian Defense Ministry announced they had deployed weapons and equipment to Kursk to beef up support as the government declared a federal emergency in the region. Videos released by Russian press showed columns of military trucks carrying artillery pieces and tanks.

Overnight, air raid alarms were activated in Ukraine’s Sumy region—  which borders the Kursk oblast— and Ukrainian authorities began evacuating about 20,000 people from the area on Friday.  

Ukraine’s General Staff of the Armed Forces confirmed Friday they attacked a military airfield in the Russian oblast of Lipetsk, targeting an ammunition depot that contained missiles. Videos posted by local media and residents showed a large-scale fire breaking out due to the explosion. 

The Russian government evacuated people living near the air base after Ukraine’s “massive attack” caused explosions, disrupted power supply, and injured nine people, the regional governor Igor Artamonov said via Telegram. 

In a sign that Ukrainian forces may intend to hold the territory they have captured, videos are being released showing signs of Russian towns now spelled with the Ukrainian spelling and a Ukrainian flag under the names. 

A video shows soldiers from the 61st Brigade speaking at the Gazprom offices in Sudzha, located in the Kursk region. “The city is under the control of the armed forces of Ukraine and quiet,” the Ukrainian soldiers said. 

The capture of Sudzha could mark a strategic boost for Kyiv because it is the junction for two major Russian gas pipelines, bringing energy supplies to the West from Siberia and the Arctic.

Control of the gas pipeline hub — a “strategic prize,” as the Sun’s James Brooke has reported, could be used as a “bargaining chip” in potential armistice talks between Russia and Ukraine.

Meduza, a Latvia-based independent Russian news website, reports that Ukrainian forces had captured the “gas metering station” at Sudzha, which it describes as “the last remaining Russian pipeline still sending gas to Europe through Ukraine.” Gas is still flowing through the pipeline, though, Meduza says. 

Local press reported Saturday that Russian forces have been deployed to defend the Kursk Nuclear Power Plant — another potential strategic target for Kyiv — as Ukrainian forces extend their attack further into Russia. The plant is located at the city of Kurchatov and is 49 miles away from Ukrainian-held Sudzha. 

The International Atomic Energy Agency, known as the IAEA,  has expressed concern over the military activities near the plant. The president of the IAEA, Rafael Mariano Grossi, released a statement reminding both the Russian and Ukrainian governments of the protocols to ensure nuclear safety during an armed conflict. 

“I would like to appeal to all sides to exercise maximum restraint in order to avoid a nuclear accident with the potential for serious radiological consequences,” Mr. Grossi said in a statement. “I am personally in contact with the relevant authorities of both countries and will continue to be seized of the matter.”

The Ukrainian government has not released any information on the operation in the Kursk region. 

A senior advisor to President Zelensky of Ukraine, Mykhailo Podolyak, said on social media that a significant part of the international community now considers Russia a target for operations.

“The impossible has become possible, and the mythical ‘Russian brutality and boundlessness’ has turned against Russia itself,” Mr. Podolyak wrote. 

Analyst Emil Kastehelmi, from the Finland-based organization that analyzes military movements on Russia’s war in Ukraine, Black Bird Group, wrote that the invading Ukrainian units have successfully exploited the disorganization of Russia’s defense — for now. 

“Time is also running against Ukrainians. Russian won’t be disorganized forever,” Mr. Kastehelmi warns. “At least in the information space, Russians are suffering an embarrassing defeat, and the media is again focused on Ukrainian successes.”