South Korea's spy agency said Friday it believes North Korea has decided to send large-scale troops to support Russia in its war against Ukraine and has already begun deployment, raising concerns over military cooperation expanding beyond their arms trade. The National Intelligence Service's (NIS) assessment came after South Korean President Yoon Suk Yeol convened an emergency security meeting amid mounting speculation that the North may be providing its soldiers to fight Russia's war in Ukraine. Following the meeting, the NIS said it has learned that the North has recently decided to send four brigades of 12,000 soldiers, including special forces, to the war in Ukraine, which would mark North Korea's first large-scale deployment of ground forces. An NIS source said the mobilization of the troops has "already begun." The presidential office said South Korea has been closely tracking North Korea's troop movement to Russia from the beginning in coordination with its allies, and will continue to monitor the situation and take all necessary measures proactively. The North's deployment signals a major development in the military cooperation between Moscow and Pyongyang besides their suspected arms trade, already criticized by the international community. Moscow and Pyongyang have recently forged closer ties, with President Vladimir Putin and North Korean leader Kim Jong-un signing a new partnership treaty that includes a mutual defense clause during their summit in Pyongyang in June. On Thursday, Ukrainian President Volodymyr Zelenskyy cited Ukrainian intelligence reports indicating that North Korean personnel have already been deployed in Russian-occupied Ukrainian territories, with an additional 10,000 troops being prepared to join the fight. Zelenskyy suggested that Russia is relying on North Korean forces to compensate for its substantial troop losses, as many young Russians seek to avoid conscription. Source: Yonhap News Agency