South Korea on Tuesday pledged to take "phased measures" in response to growing military cooperation between North Korea and Russia, although the specific actions have yet to be disclosed.
Seoul urged Pyongyang to "immediately withdraw troops from Russia," according to a report by South Korean news agency Yonhap. The South Korean government claims North Korea has already sent 1,500 troops to Russia and is considering sending an additional 10,000 soldiers.
Neither North Korea nor Russia has commented on Seoul's accusations, though the Kremlin has defended its right to develop relations with Pyongyang, calling it a matter of Russian sovereignty.
The US, a key ally of South Korea, has not confirmed the claims that North Korean troops have been deployed to Russia.
NATO has also sought more information, with South Korea providing a briefing on the situation. Alliance chief Mark Rutte spoke with South Korean President Yoon Suk Yeol on Monday, stating that if confirmed, the deployment of North Korean troops to support Russia in Ukraine would represent a "significant escalation."
In a potential further step, Seoul is considering sending a team to Ukraine to monitor the alleged deployment of North Korean soldiers, Yonhap reported.
