North Korea foreign minister heads to Russia as Biden warns of 'dangerous' situation

The Pentagon said there are now 10,000 North Korean troops in Russia.

LONDON -- North Korea's Foreign Minister Choe Son-hui left Pyongyang on Monday night for an official visit to Russia, North Korean state-controlled media reported, as the U.S. and NATO again denounced growing military cooperation between the two neighbors.

The Korean Central News Agency said Choe and her entourage departed Pyongyang International Airport on Monday, with Moscow's ambassador to the country Alexander Matsegora among those who saw the delegation off.

The visit "is taking place within the framework of a strategic dialogue -- following an agreement to enhance ties reached by the leaders of our countries during the June 2024 summit," a foreign ministry statement said.

The visit comes as Western concerns grow about the presence of North Korea troops in Russia ahead of their expected deployment to reinforce Moscow's troops fighting Ukrainian forces in eastern Ukraine and western Russia.

In this photo provided by the North Korean government, North Korean Foreign Minister Choe Son Hui (C) prepares to depart for Russia from Pyongyang, North Korea, on Oct. 28, 2024.

Korean Central News Agency/Korea News Service via AP

President Joe Biden on Monday commented on the situation after casting his vote for next week's elections in Delaware.

"It's very dangerous, very dangerous," Biden told reporters.

Pentagon spokesperson Sabrina Singh told reporters at a Monday briefing that the U.S. believes there are now 10,000 North Korean troops in Russia, up from the American estimate of 3,000 given by National Security Council spokesperson John Kirby last week.

The troops have been sent "to train in eastern Russia" and "will probably augment Russian forces near Ukraine over the next several weeks," she said.

Singh said some of Pyongyang's troops are moving towards Russia's western Kursk region, where Ukrainian forces established a foothold in August.

"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," she said.

Singh -- like Kirby and Defense Secretary Lloyd Austin last week -- framed the deployment as a sign of Moscow's weakness.

Members of the Korean Vietnam War Veterans Association wave national flags during a rally against a recent deployment of North Korean troops to Russia, in Seoul, South Korea, on Oct. 28, 2024.

Ahn Young-joon/AP

"This would mark a further escalation and highlights President [Vladimir] Putin's increasing desperation, as Russia has suffered extraordinary casualties on the battlefield, and an indication that Putin may be in more trouble than people realize," she said.

"He's tin-cupping to the DPRK, Iran, because he has failed to meet those battlefield objectives," Singh added, using the acronym of the country's official name -- the Democratic People's Republic of Korea.

ABC News' Ellie Kaufman, Matthew Seyler and Justin Gomez contributed to this report.