Ukrainian President Volodymyr Zelenskyy said on Saturday his troops had strengthened positions and expanded territory in Russia’s Kursk region nearly two weeks into their incursion.

Ukraine says it has seized more than 80 settlements over 1,150 square kilometers (444 square miles) in Kursk since August 6 in the biggest invasion of Russia since World War II.

Zelenskyy said his army chief, Oleksander Syrskyi, had reported that Ukrainian troops continued their advance and took more Russian soldiers as prisoners.

“Thank you to all the soldiers and commanders who are taking Russian military prisoners and bringing the release of our soldiers and civilians held by Russia closer,” Zelenskyy said in a statement on the Telegram messaging app.

“General Syrskyi also reported on strengthening our forces’ positions in the Kursk region and expanding the stabilized territory.”

The Ukrainian military said in its daily report that troops were successfully advancing further in Kursk, without offering more details. It had previously reported 35 kilometers (almost 22 miles) of advances.

Reuters could not independently verify the battlefield developments.

Russia has called the incursion a major provocation and vowed to retaliate with a “worthy response,” more than 2½ years since it launched a full-scale invasion of Ukraine.

Moscow says Ukraine has been using Western arms, including probably U.S.-made HIMARS rockets to destroy a bridge and kill volunteers trying to evacuate civilians.

Zelenskyy also said that Ukrainian troops had repelled dozens of Russian attacks near Pokrovsk and Toretsk in Ukraine’s Donetsk region. The military said 51 Russian attacks were stopped near Pokrovsk, a major logistics hub in the eastern region, and another 13 near the town of Toretsk in the last 24 hours.

“Our soldiers and units are doing everything to destroy the occupier and repel the assaults. The situation is under control,” Zelenskyy said.