(LONDON) -- Ukrainian forces on Sunday launched a new offensive inside Russia's western Kursk border region, going on the attack with substantial forces according to reports from Russian and Ukrainian military bloggers.
Russia's Defense Ministry reported a large-scale attack by Kyiv's forces involving armored columns that began on Sunday morning, with Ukrainian troops attacking in three directions inside Kursk.
Ukraine first seized a foothold inside the Kursk region with a surprise offensive in August. But Kyiv's forces have since been slowly pushed back by Russia, including recently with support from North Korean troops.
A Ukrainian military source confirmed to ABC News that a new offensive operation had begun.
The head of Ukrainian President Volodymyr Zelenskyy's office, Andrii Yermark, also appeared to cryptically confirm the offensive, writing on Telegram: "Kursk Oblast, good news! Russia is getting what it deserves."
Andrii Kovalenko, head of Ukraine's counter-disinformation center, also wrote that Ukrainian troops have gone on the attack in multiple directions inside Kursk.
Videos posted to Russian military blogger channels appeared to show columns of Ukrainian armored vehicles on the move. The Ukrainian assault appears to be Kyiv's most substantial offensive operation in Kursk since August.
Multiple Russian military bloggers reported that Ukrainian troops, tanks, armored vehicles and demining equipment attacked the villages of Berdin and Bolshoye Soldatskoye, north of Sudzha -- the main administrative border town that Ukraine captured in August.
Bloggers also reported an attack further west on the border town of Tetkino.
Prominent Russian military bloggers -- some close to Russia's Defense Ministry -- said that the offensive was expected but that the situation is challenging for the Russian defenders.
The Defense Ministry said in a statement that two assaults were repelled. "The operation to destroy the Ukrainian Armed Forces formations continues," it wrote on Telegram.
Ukrainian troops appeared to make small advances on Sunday but did not achieve significant breakthroughs of the Russian lines, according to open-source monitors. Some Russian military bloggers said they believe Ukraine will attempt another push through Monday, with others suggesting Kyiv's main attack was yet to come.
The new Ukrainian assault comes just two weeks before President-elect Donald Trump returns to the White House, with the expectation that his new administration will push for a peace deal to end the nearly 3-year-old war.
ABC News' Natasha Popova contributed to this report.
Copyright © 2025, ABC Audio. All rights reserved.