KYIV, Ukraine — Ukrainian forces pushed on with their major cross-border advance into Russia’s Kursk region for a second week Wednesday, claiming that they took more ground, captured more Russian prisoners and destroyed a bomber in attacks on military airfields.

Assault troops advanced 1 to 2 kilometers (about a mile) farther into areas of Kursk on Wednesday, the commander of the Ukrainian military, Gen. Oleksandr Syrskyi, said in a video posted on President Volodymyr Zelenskyy’s Telegram channel.

Ukrainian troops also took more than 100 Russian soldiers prisoner, Syrskyi said. Zelenskyy said they would eventually be swapped for Ukrainian prisoners of war.

Additionally, the troops destroyed a Russian Su-34 jet used to launch devastating glide bombs at Ukrainian front-line positions and cities, Ukraine’s General Staff said.

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Surprise Push Rattles Kremlin

The surprise Ukrainian push into the Kursk region that began Aug. 6 has rattled the Kremlin. The daring operation is the largest attack on Russia since World War II and could involve as many as 10,000 Ukrainian troops backed by armor and artillery, military analysts say.

Syrskyi claims Ukrainian forces have advanced into 1,000 square kilometers (about 390 square miles) of the Kursk region, though it was not possible to independently verify that claim.

If true and if Ukraine actually controls all of that territory in the Kursk region, it would have captured in just one week almost as much Ukrainian land as Russian forces took — 1,175 square kilometers (450 square miles) — between January and July this year, according to calculations by the Institute for the Study of War, a Washington-based think tank.

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Russia Acknowledges Ukrainian Gains

Russian authorities acknowledged the Ukrainian gains in the Kursk region, but they described them as smaller than what Kyiv has claimed. Even so, they have evacuated about 132,000 people from the Kursk and Belgorod regions and have plans to evacuate another 59,000 more.

Ukraine’s deputy prime minister, Iryna Vereschuk, said Wednesday that the military plans to open humanitarian corridors that would allow civilians in Ukraine-controlled areas of the Kursk region to head elsewhere in Russia or into Ukraine.

Ukraine also claimed that overnight Tuesday into Wednesday, it conducted its biggest attack on Russian military airfields since the start of the Kremlin’s full-scale invasion in February 2022.

A Ukrainian security official told The Associated Press that the aim was to sap Russia’s air power advantage. He spoke on condition of anonymity because he was not authorized to speak publicly.

A Ukrainian Foreign Ministry spokesperson said Tuesday that Kyiv has no intention to occupy the Russian territory it controls. Rather, it aims to stop Russia from firing missiles into Ukraine from Kursk, he said.

Analysts say Kyiv’s forces targeted the Kursk region because Russia’s weak command and control structure there made it vulnerable.

“The situation is still highly fluid, but with clear signs that the Russian command and control of responding units is still coming together, with all-important unity of command not yet achieved,” said retired U.S. Vice Adm. Robert Murrett, a professor and deputy director of Syracuse University’s Institute for Security Policy and Law. “The next 2-3 days will be critical for both sides.”

In AP video shot in Ukraine’s Sumy region, which borders Kursk and which analysts say is serving as a staging ground for the cross-border advance, Ukrainian trucks and armored vehicles traveled along roads lined with thick forests.

Meanwhile, Russia’s Belgorod border region, which is next to Kursk, declared a regional emergency Wednesday during heavy Ukrainian shelling. A federal emergency was declared in Kursk on Saturday.

Belgorod Gov. Vyacheslav Gladkov described the situation there as “extremely difficult and tense,” as the attacks destroyed homes and caused civilian casualties, unnerving locals.

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Children, in particular, are being moved to safety, Gladkov said on his Telegram channel, adding that about 5,000 children were in camps in safe areas. He said the previous day that roughly 11,000 people had fled their homes, with about 1,000 staying in temporary accommodation centers.

It wasn’t clear how, when — or whether — Ukraine would attempt to extricate itself from the ground it has taken. The Ukrainian military claims it controls 74 settlements, believed to be villages or hamlets, in the Kursk region.

Ukraine’s 1+1 TV channel published a video report Wednesday that it said was from Sudzha, a Russian town about 10 kilometers (6 miles) from the border. The report showed burned-out columns of Russian military vehicles, and Ukrainian soldiers handing out humanitarian aid to local residents and removing Russian flags from an administrative building.

Russia’s predicament is whether to pull troops from the front line in Ukraine’s Donetsk region, where achieving a breakthrough is one of the Kremlin’s primary war goals, to defend Kursk and halt the Ukrainian advance.

U.S. President Joe Biden said Tuesday that the developments in Russia are “creating a real dilemma” for Russian President Vladimir Putin. Biden declined to comment further on the top-secret operation until it is over.

The Institute for the Study of War said the incursion is unlikely to shift the dynamics of the conflict.

“Russian authorities will likely remain extremely averse to pulling Russian military units engaged in combat from (Donetsk) and will likely continue deploying limited numbers of irregular forces to Kursk … due to concerns about further slowing the tempo of Russian operations in these higher priority directions,” it said late Tuesday.

A woman in Belgorod told the AP on Tuesday that the Ukrainian shelling had been more intense for about 10 days until Monday, when it was followed by a lull. The number of people in Belgorod who openly supported the war has decreased since the start of the intensified Ukrainian attacks, she told the AP, speaking on condition of anonymity because of security concerns.

“When explosions started near the city, when people were dying and when all this started happening before our eyes … and when it affected people personally, they stopped at least openly supporting” the war, the woman said.

In his nightly address Tuesday, Zelenskyy said the Kursk operation is also meant to lift the country’s spirits after 900 days of war and to make an emphatic statement about Ukraine’s military capabilities.

“Now all of us in Ukraine should act as unitedly and efficiently as we did in the first weeks and months of this war, when Ukraine took the initiative and began to turn the situation to the benefit of our state,” Zelenskyy said.