The United States is concerned by Russia's growing relationship with North Korea and by what technology the two countries may be exchanging, the top U.S. arms control official said on Wednesday.

YONHAP]   The secretary general of South Korea's presidential advisory body on unification said Tuesday that North Korea would not engage in dialogue with the United States as long as it is being paid by Russia for its troop deployment and other forms of military cooperation.

North Korea ratified a major defense treaty with Russia stipulating mutual military aid, the North’s state media reported Tuesday, as the U.S., South Korea and Ukraine say North Korea has sent thousands of troops to Russia to support its war against Ukraine.

North Korean troops have begun engaging in combat operations alongside Russian forces, the U.S. State Department said on Tuesday, expressing concern that Russia had turned to North Korea for soldiers to fight in its war with Ukraine.

North Korean soldiers deployed to the Kursk region of Russia have begun combat operations against Ukrainian troops, the U.S. State Department confirmed Tuesday.

South Korea's spy agency said Wednesday that North Korean troops dispatched to Russia are "already engaging in combat operations" against Ukraine. "North Korean soldiers dispatched to Russia have moved to the Kursk region over the past two weeks and their deployment to battlefields has been completed,