Ukraine's top military commander says its forces are still defending a small area of territory inside Russia that it captured almost a year ago.
In August 2024 Ukraine launched a surprise incursion into the Kursk region, capturing more than 1,000 sq km (386 sq miles) of Russian land.
Ukraine's commander-in-chief Oleksandr Syrsky said 10,000 Russian troops are attempting to drive his forces back.
While Russia has repeatedly insisted it had recaptured the entire region, Syrsky said on Sunday that Ukraine is still holding around 90 sq km (56 sq miles) in the Kursk region.
Speaking to reporters on Sunday, Syrsky vowed to increase the "scale and depth" of strikes on Russia.
"Of course, we will continue," he said.
"Given that we are not fighting against the population, we are fighting and destroying purely military targets."
Ukraine seized dozens of villages in the Kursk region shortly after its incursion started on 6 August 2024.
President Volodymyr Zelensky said the Kursk operation established a buffer zone which prevented Russian forces from being deployed in key areas of the front in eastern Ukraine.
But, Kyiv's advances stalled after Russia rushed reinforcements to the area - including thousands of troops from its ally North Korea.
In recent months Ukrainian forces have been in retreat in Kursk after facing 70,000 Russian troops and heavy drone attacks as part of Moscow's drive to regain the territory.
Last autumn, North Korea sent an estimated 11,000 troops to Kursk to fight off the Ukrainian cross-border incursion.
Western officials told the BBC in January that at least 1,000 North Korean troops in Russia had been killed in just three months.
Earlier this month, the government in Pyongyang promised to send thousands of mine-clearing troops and builders to Russia's Kursk region to restore damaged infrastructure.
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