Ukrainian forces on Sunday launched a new offensive inside Russia's western Kursk border region, going on the attack with substantial forces.

The surprise attack seeks to reverse Ukraine’s decreasing hold of the region. Since Kyiv’s forces gained partial control of Kursk following a daring cross-border assault last August, Russian troops, aided by North Korean soldiers, have halved the territory held by Ukraine, albeit while suffering thousands of casualties.

Ukrainian President Volodymyr Zelenskiy said on Monday that Russia had suffered heavy losses in five months of fighting Ukrainian forces in southern Russia's Kursk region, with nearly 15,000 killed.