Ukrainian President Volodymyr Zelensky has said there have been more than 3,000 North Korean casualties in Russia's Kursk region.

Despite their elite status, North Korea's "Storm" troops were ill-prepared for the war, South Korea's National Intelligence Service said.

North Korean troops have now entered Russia’s war with Ukraine in a major way, and some have been killed, Western officials say.

North Korean soldiers fighting for Russia were given fake military documents with Russian names and birthplaces, the Ukrainian military said, amid claims from Kyiv that Russia is trying to conceal the presence of foreign fighters on the battlefield.

Despite the relatively high casualty rate, Zelensky added that North Korea might send even more resources to Russian dictator Vladimir Putin’s armies.

South Korea's military has said that North Korea is preparing to continue aiding Russia in its war with Ukraine, despite casualties.

"Through various sources of information and intelligence, we assess that North Korean troops who have recently engaged in combat with Ukrainian forces have suffered around 1,100 casualties," the JCS said in a statement.

North Korean troops are suffering heavy losses in the fighting in Russia's Kursk region and are facing logistical difficulties as a result of Ukrainian attacks, Ukraine’s military intelligence said Thursday.

The North Korean army is one of the world’s largest.​ As it joins Russia’s war against Ukraine, its soldiers are paying a price for Kim Jong-un’s geopolitical maneuvers.

N. Korea’s military involvement in Russia’s war against Ukraine is intensifying, with recent offensives near Kursk resulting in heavy losses among DPRK troops and increasing calls for reinforcements.

The secretive nature of succession means that no one outside its highest elites know who could replace Kim Jong Un if he resigns or dies in office.