The assessment came two days after North Korea confirmed for the first time that it had sent combat troops to help Russia recapture parts of the Kursk region, which it lost control of to a surprise Ukrainian incursion last year.

U.S., South Korean and Ukraine intelligence officials have said that North Korea last fall dispatched about 10,000-12,000 troops to Russia.

North Korea's involvement in the war has sparked fears of global escalation, with Seoul especially concerned of Pyongyang's troops gaining experience.