North Korea
"These are not battle-hardened troops. They haven't been in combat before."
Moscow will now be forced to respond, apparently.
He said a quick ceasefire would be "a loss" for his country.
Some 10,000 fighters are believed to have been sent to the region.
Volodymyr Zelenskyy has called for a "strong response" from global leaders.
Alexander Lukashenko said the Russian president "would never" do such a thing.
"We can be certain [North Korea] will ask for a high price from Russia in return," the UK's ambassador to the UN claimed.
North Korea and Russia signed a mutual defence pact earlier this year.
South Korea's defence minister warned there's a strong possibility Russia is taking soldiers from the Asian dictatorship.
Russia's ally seemed to overlook all of Moscow's warnings towards the West over the years.
About North Korea
North Korea is led by Kim Jung-un. In December it launched a long range rocket, defying warnings from the UN and Washington. In April, North Korea defied international warnings by launching a similar rocket, however the craft disintegrated seconds after launch, causing considerable embarrassment to the regime.