TOPSHOT - This aerial photograph taken on February 1, 2024, shows residential buildings destroyed by shelling in Izyum, Kharkiv region, amid the Russian invasion of Ukraine. (Photo by Roman PILIPEY / AFP) (Photo by ROMAN PILIPEY/AFP via Getty Images)
CNN  — 

A small number of North Korean troops are already inside Ukraine, according to two western intelligence officials, and officials expect that number to grow as the North Koreans complete training in eastern Russia and move toward the front lines of the war.

The North Korean troops’ presence inside Ukraine goes a step beyond what NATO and the Pentagon confirmed on Monday, which is that roughly 10,000 North Korean troops are training in eastern Russia with some en route to Russia’s Kursk region. Ukrainian troops have held territory inside Kursk since August.

“It seems that a good many of them are already in action,” one of the officials said on Tuesday, referring to the North Koreans. Ukrainian President Volodymyr Zelensky said last week that Ukrainian intelligence assessed that the troops would start to enter combat zones on Sunday.

A US official said the US can not yet corroborate reports that North Koreans troops are already inside Ukraine. The US has been playing catchup, however, when it comes to North Korea’s deployments — US officials did not confirm publicly that the troops were in Russia until weeks after South Korea first alleged it.

US and South Korean diplomatic and military officials are meeting in Washington, DC this week to discuss the deployment and North Korea’s “expanding relationship with Russia” more broadly, State Department spokesperson Matthew Miller said on Monday.

Separately, top Ukrainian official Andriy Yermak is in the US capital Tuesday for meetings with National Security Adviser Jake Sullivan and Secretary of State Antony Blinken. Yermak said he and Sullivan discussed the “North Korean soldiers whom Russia is preparing for war.”

South Korean officials also traveled to NATO headquarters on Monday and briefed allies on the North Korean deployments. NATO allies have been hoping that the intelligence spurs South Korea to begin providing military aid to the Ukrainians, which would be at odds with the South Koreans’ longstanding policy of not arming countries at war. But South Korea’s president has signaled an openness to changing that policy.

“While we have maintained our principle of not directly supplying lethal weapons, we can also review our stance more flexibly, depending on the level of North Korean military activities,” South Korean President Yoon Suk Yeol said last week.

It is still unclear how helpful the North Koreans will be to the Russians on the battlefield. Many of the troops deployed are special forces, the sources said, and intelligence assessments suggest that the North Korean government believes their troops have more combat power than regular Russian troops because they are better trained and specialized, officials said.

But North Korea’s military has not fought in an actual war for over 70 years, and intelligence officials believe the North Korean government sent them in large part so they could gain combat experience.

Officials also expect that at least some of the troops will desert their units once they get to the battlefield, and that the language barrier with the Russians will be a significant impediment to conducting seamless operations. The Russians have been teaching North Korean soldiers basic Russian commands in training, like “fire” and “in position,” South Korean lawmakers told reporters on Tuesday.

Some Russian troops are already raising concerns about how the North Korean soldiers will be commanded and provided with ammunition and military kit and have wondered “what the f**k to do with them,” according to audio intercepted by Ukraine’s Defense Intelligence on October 23 from encrypted Russian transmission channels.

The intercepts also reveal plans to have one interpreter and three senior officers for every 30 North Korean men, CNN has reported.

‘The number may rise’

Many of the public assessments that have emerged on North Korea’s troop movements have come to light via South Korean lawmakers speaking to the media after briefings with the country’s intelligence services.

On Wednesday, two lawmakers – Lee Seong-kweun and Park Sun-won – spoke to reporters after a closed door briefing from the Defense Intelligence Agency (DIA). Their assessment was that North Korea had sent members of its elite XI Army Corps to Russia, which specialize in urban terrain and infiltration. But the DIA questioned such a unit’s effectiveness in the more open terrain of the Kursk region.

The DIA added that there was not exact information on whether North Korean troops have been sent to fighting positions, but there “is a possibility that an advance team may have been sent to the frontline,” the lawmakers said.

South Korean intelligence has put the number of North Korean troops inside Russia right now at about 13,000, higher than the US and the UK. The number could go up further — the US has already revised its assessment upward from last week, when the White House assessed that only about 3,000 North Korean troops were in Russia.

“The number may rise,” a third western official said. “Allies and partners across the globe are watching and consulting and will proactively share intelligence on the matter as it affects the security of the Euro-Atlantic and Indo-Pacific regions and beyond.”

In addition to military personnel, North Korea has provided Moscow with 11,000 containers of ammunition consisting of around 2 million artillery rounds since last year, a senior NATO official told CNN earlier this month.

The US has also been urging China, which maintains a relationship with Pyongyang, to intervene and pressure the North Koreans to pull back, officials said.

Sullivan “directed the US government to engage the PRC and to organize an effort to get other countries to reach out to the PRC as well over our concerns about DPRK sending troops into Russia and the implications of that,” a US official told CNN, referring to China.

“We have communicated with the PRC about this matter to make clear that we are concerned about it, and that they ought to be concerned about this destabilizing action by two of its neighbors, Russia and North Korea,” Miller said.

Western officials are not optimistic, however, that China will intervene with North Korea’s plans, the sources said. China has continued to be a “critical enabler” of Russia’s war effort, according to the NATO official, and is still fueling Russia’s defense industry with substantial amounts of dual-use goods like microelectronics and machine tools that can be used to build weapons.

CNN’s Haley Britzky and Jennifer Hansler contributed reporting.