WASHINGTON (Reuters) - Ukraine would not see any new restrictions on the use of U.S. weapons against North Korean forces should they enter the fight against Ukrainian forces, the Pentagon said on Monday, as it estimated 10,000 North Korean troops had been deployed to eastern Russia for training.

"A portion of those soldiers have already moved closer to Ukraine, and we are increasingly concerned that Russia intends to use these soldiers in combat or to support combat operations against Ukrainian forces in Russia's Kursk Oblast near the border with Ukraine," said Pentagon spokesperson Sabrina Singh. NATO Secretary General Mark Rutte said earlier on Monday that military units from North Korea have been deployed to Russia's Kursk region, which Ukrainian forces grabbed in a surprise summer offensive.

Singh declined to confirm North Korean forces were present in Kursk.

"It is likely that they are moving in that direction towards Kursk. But I don't have more details just yet," Singh said.

(Reporting by Phil Stewart)