Ukraine says North Korean soldiers have fought on Russia's side against Ukrainian troops trying to hold territory in Russia's Kursk region. Moscow has neither confirmed nor denied the presence of North Korean troops on its soil.
Russian President Vladimir Putin and North Korean leader Kim Jong-un signed a "Comprehensive Strategic Partnership Treaty" during Putin's visit to Pyongyang in June.
The pact includes a mutual defence pact for immediate military assistance if either faces armed aggression.
MNA/