A US media outlet says North Korean soldiers have not been spotted recently on the front lines of fighting between Ukraine and Russia.

Quoting Ukrainian and US officials, the New York Times reported on Thursday, "The North Korean troops, sent to bolster Russian forces trying to push back a Ukrainian offensive inside Russia's borders, have not been seen at the front for about two weeks."

In the report, the US officials said the pullout may not be permanent. They were also quoted as saying, "The North Koreans could return after receiving additional training or after the Russians come up with new ways of deploying them to avoid such heavy casualties."

It is said that about 11,000 of the North Korean soldiers have been deployed to the Kursk region in western Russia, where Ukrainian forces have conducted cross-border attacks.

Ukrainian President Volodymyr Zelenskyy said in January that some 4,000 North Korean soldiers had been killed or wounded.