Officials in Ukraine and South Korea have accused North Korea of dispatching troops, estimated to number in the thousands perhaps, to aid Russia in the war in Ukraine.

South Korea has summoned the Russian ambassador, seeking the "immediate withdrawal" of North Korean troops which it says are being trained to fight in Ukraine. About 1,500 North Korean soldiers, including those from the special forces, have already arrived in Russia, according to Seoul's spy agency.

September was the bloodiest month of the war for Russian forces in Ukraine, U.S. officials said, with the costly offensive in the east bringing the number of Russia’s dead and wounded to more than 600,000 troops since the war started.