WASHINGTON

The Pentagon said Tuesday that a "small number" of North Korean troops are already in Russia's Kursk region.

"As we highlighted earlier this week, we believe that the DPRK (Democratic People’s Republic of Korea) has sent approximately 10,000 soldiers in total to train in eastern Russia, and that these troops will probably augment Russian forces near Ukraine over the next several weeks.

"A portion of those soldiers have already moved closer to Ukraine, towards Russia's Kursk Oblast, near the border with Ukraine, approximately a couple thousand. With a smaller number already present in the Kursk region," Air Force Maj. Gen. Pat Ryder told reporters.

NATO Secretary-General Mark Rutte confirmed Monday that North Korean troops were already in the Kursk region in a "dangerous expansion" of the conflict.

"I'm not going to go into specific numbers, other than just to say at this point we assess it's a relatively small number," Ryder said when asked about the number.

The US "remains concerned" that Russia intends to use the soldiers in combat or to support combat operations against Ukrainian forces in Kursk, he said.

"We continue to monitor closely and are consulting with our Ukrainian partners as well as other allies and partners," Ryder added.

Separately, US President Joe Biden said he is "concerned" that North Korean troops are being trained in Russia.

Asked if Ukraine should strike the troops, Biden told reporters: "If they cross into Ukraine."

Ryder said the US has "no information right now to corroborate the reports that there are DPRK forces inside Ukraine."