North Korean soldiers have been killed fighting Ukrainian forces in the Russian border region of Kursk, the United States said.
They would be the first casualties reported since it was revealed in October that North Korea had sent around 10,000 troops to bolster Russia's war effort.
Ukraine's military intelligence agency, GUR, also said at least 30 North Korean soldiers were killed or injured in the weekend's fighting.
The BBC has not independently verified these claims.
North Korean troops, none of whom have prior combat experience, reportedly spent their first weeks in Russia training and then serving in support roles.
On Saturday, Ukrainian President Volodymyr Zelensky said Russia had begun using “significant numbers” in its assaults on Kursk, part of which has been occupied by Ukraine since launching a surprise incursion in August.
Speaking to reporters Monday, Pentagon Press Secretary Gen. Pat Ryder said the United States believed North Korean soldiers had “engaged in fighting at Kursk alongside Russian forces” and “had suffered losses, killed and wounded”.
He did not give specific numbers, but said troops had been in combat since “a little over a week ago.”
He added that it appeared the North Koreans were being used in infantry roles and their involvement had so far been limited to Kursk, implying they had not been deployed to Ukraine itself.
Russian forces, which launched a full-scale invasion of Ukraine in February 2022, have advanced into the east of the country in recent months.
The GUR said the North Korean casualties occurred on Saturday and Sunday in the Kursk villages of Plekhovo, Vorobzha and Martynovka.
On Monday, President Zelensky posted drone footage on Telegram showing a number of men hiding behind trees, claiming they were North Korean soldiers who had just taken part in an assault on a Ukrainian position .
He also released footage that he said showed Russian troops trying to hide the presence of North Koreans on the battlefield by using a campfire to burn the faces of those who had been killed.
“Ukrainian defense forces and intelligence are working to determine the true scale of losses suffered by Russian units, which include North Koreans,” he said.
He added that there was “no reason for North Koreans to die in this war.”
The Kremlin referred questions about the North Korean deaths to the Russian Defense Ministry, which had no comment.
Following reports of the deaths, the EU and countries including the UK, US, Australia and South Korea called Pyongyang's involvement in the conflict a “dangerous expansion.” .. with serious consequences for European and Indo-Pacific security.”
Earlier this week, the US Treasury Department announced sanctions against nine individuals and seven entities over their financial and military support of North Korea.
