In a meeting with Kim in Beijing, Putin also praised their countries' "trust and friendship" and said that sending the troops was the North Korean leader's idea.

North Korea has become one of Russia's main allies since it invaded Ukraine three-and-a-half years ago, sending thousands of troops and container loads of weapons to help the Kremlin push Ukrainian forces out of western Russia, following Kyiv's shock incursion last year.

"On your initiative, as is well known, your special forces took part in the liberation of the Kursk region," Putin said in a meeting with his North Korean counterpart.

"This was in full accordance with our new agreement. I would like to note that your soldiers fought courageously and heroically."

"We will never forget the sacrifices made by your armed forces and the families of your servicemen," he added.

Putin made the comments in the Chinese capital, where the two leaders were attending a massive parade marking the 80th anniversary of Japan's World War II surrender.