After a surprise offensive earlier this year, Ukraine’s forces have lost about half the territory seized in Russia’s Kursk region and may lose the rest in a matter of months, according to U.S. officials, potentially depriving Kyiv of important leverage for ceasefire talks with Russia.

Ukraine’s military is already grappling with a lack of manpower and uncertainty about the future flow of supplies from the U.S. and other allies, even as it struggles to fend off Russian advances in its east. In Kursk, the region in western Russia where Ukrainian forces seized a swath of land, Ukrainian troops are also facing off against about 12,000 North Korean troops reinforcing the Russians.

With a more concerted effort by Moscow to push Ukrainian troops out of Kursk, possibly as soon as next month, Kyiv’s forces may only be able to hold the land until spring before they are forced to retreat — or risk being encircled — the U.S. officials said, speaking on condition of anonymity to discuss their confidential assessments.