Ukrainian President Volodymyr Zelenskyy has confirmed the Ukrainian military's first combat engagement with North Korean troops, saying it opened a new chapter of instability in the world.

Zelenskyy, in a video address posted on the Ukrainian president's official website Tuesday, said, "The first battles with North Korean soldiers open a new page of instability in the world."

"I want to thank everyone in the world who reacted to the deployment of North Korean soldiers in Russia. And who reacted not only with words, but also by preparing appropriate actions to support our defense here in Ukraine," he said.

"Together with the world, we must do everything to make this Russian step to expand the war -- to really escalate it -- to make this step a failure. Both for them, and for North Korea," he added, according to a transcript posted on the website.

In a Tuesday interview with local broadcaster KBS, Ukraine's Defense Minister Rustem Umerov confirmed that the first battle with North Korean soldiers has already taken place on a "small scale."

Earlier Monday, Zelenskyy said some 11,000 North Korean soldiers were already in Russia's western front-line Kursk region.

The US State Department also confirmed that as many as 10,000 North Korean troops are in Kursk, saying they could engage in combat in the "coming days." (Yonhap)