KYIV (Reuters) - Ukraine has lost over 40% of the territory in Russia's Kursk region that it captured in a surprise incursion in August as Russian forces have mounted waves of counter-assaults, a senior Ukrainian military source said.

Moscow's soldiers have 'recently advanced' in the segment under Ukrainian control in Kursk, according to the Institute for the Study of War (ISW).

Russian forces have managed to reclaim territory from Ukrainian soldiers in the Kursk region, new assessments have found.

Ukraine has lost over 40 per cent of the territory captured in Russia’s Kursk region as Russian forced mount waves of counter assaults.

Ukrainian forces hit a radar station of an S-400 anti-aircraft missile system in Russia's Kursk Oblast on the night of 23-24 November. Source: Ukraine's General Staff Details: The General Staff reported that Ukrainian troops had struck the positions of an anti-aircraft missile division from the 1490th Guards Anti-Aircraft Missile Regiment of the 6th Army of the Russian Federation in Kursk Oblast.

Ukraine has lost over 40% of the territory in Russia's Kursk region that it seized in a surprise incursion in August as Russian forces have mounted waves of counter-assaults, a senior Ukrainian military source said.

Ukraine has now lost more than 40% of the territory of Kursk Oblast, which it has controlled since August, as a result of Russian counterattacks, says a Reuters source in the General Staff of the Ukrainian Armed Forces.