Seoul "will not stand by but respond firmly in collaboration with the international community," South Korea said.

U KRAINE’S PRESIDENT, Volodymyr Zelensky, declared last week that North Korea is sending troops to Russia, in effect joining the invasion as a co-combatant. The appearance of one of the world’s most erratic and heavily-armed nations in the fight might test the best resourced and well-rested defences.

"We can be certain [North Korea] will ask for a high price from Russia in return," the British ambassador to the United Nations claimed.