The United States expects that thousands of North Korean soldiers in Russia will be sent into combat against Ukrainian forces “in the coming days,” U.S. Secretary of State Antony Blinken said Thursday.

The Biden administration publicly revealed new information it says it has that some 8,000 North Korean troops are now in Russia’s Kursk region near Ukraine’s border — a number far above previous comments that only “some” soldiers had deployed to the area.

“We’ve not yet seen these troops deploy into combat against Ukrainian forces, but we would expect that to happen in the coming days,” Blinken said at a news conference in Washington with U.S. Defense Secretary Lloyd Austin and their South Korean counterparts.

Blinken said Russia’s military has been training the North Korean troops in artillery, drones and basic infantry operations, “indicating that they fully intend to use these forces in front-line operations.”

“Should these troops engage in combat, or combat support operations against Ukraine, they would become legitimate military targets,” he said.

Blinken said Russia’s use of North Korean troops shows Moscow is “desperate” as its war against Ukraine enters another winter, nearly three years after it first invaded the country. The Kremlin’s forces have struggled to push back a Ukrainian incursion into Kursk that began in August — the first time Ukrainian fighters had breached Russian territory since the war began — and the two sides have been in a near-stalemate for well over a year.

Yet the involvement of North Korea in Russia’s invasion has ignited global fears about an expansion of the war and what aid Russia might be giving North Korea in exchange.

Click to play video: 'North Korea sparks concern after firing long-range intercontinental ballistic missile'

The U.S. and South Korean officials spoke hours after North Korea test-fired an intercontinental ballistic missile for the first time in almost a year, demonstrating a potential advancement in its ability to launch long-range nuclear attacks on the mainland U.S.

As the meeting in Washington was underway, the U.S., South Korea and Japan released a joint statement condemning the missile launch as a “flagrant violation” of numerous U.N. Security Council resolutions and criticizing the deepening military co-operation between North Korea and Russia, particularly the deployment of the North Korean troops.

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The U.S. has estimated there are about 10,000 North Korean troops in Russia. Seoul and its allies assess that the number has increased to 11,000, while Ukraine has put the figure higher, at up to 12,000.

Click to play video: '‘Dangerous’: North Korea sending troops to Ukraine causes alarm worldwide'

The information about North Korean troops in Kursk was first revealed in a dramatic moment during a UN Security Council meeting earlier Thursday, when the deputy U.S. ambassador to the United Nations, Robert Wood, asked for more time to add to earlier comments condemning Russia and North Korea’s growing military ties.

“We just received some information, just coming in now, that right now there are some 8,000 DPRK soldiers in Kursk Oblast,” Wood said, using the acronym for the Democratic People’s Republic of Korea, or North Korea.

“And I have a very respectful question for my Russian colleague: does Russia still maintain that there are no DPRK troops in Russia? That’s my only question and final point.”

The Russian representative at the meeting, called by Moscow to discuss international peace and security, did not respond to the comment. The session was then adjourned.

The new figure from Wood is a dramatic increase from a day earlier, when Austin would only say “some” of the troops had moved toward Ukraine’s border in the Kursk region.

North Korea also has provided munitions to Russia, and earlier this month, the White House released images it said were of North Korea shipping 1,000 containers of military equipment there by rail.

Russia and North Korea signed an expanded security agreement earlier this year.

— with files from The Associated Press