In December 2025, South Korean and Russian diplomats held a closed-door session in Moscow to address concerns over North Korea’s expanding nuclear arsenal. The talks involved South Korea’s foreign ministry and Oleg Burmistrov, representing Russian policy on North Korea.
The push for dialogue toward arms control and more peaceful diplomacy on the Korean Peninsula comes amid South Korea’s new policy of dialogue with the North under President Lee Jae Myung. With Russia intensifying its relationship with the DPRK, Seoul is looking to the Kremlin as an intermediary.
Nevertheless, questions remain on whether North Korean dictator Kim Jong Un is willing to engage in talks with the ROK after several years of disengagement and incidents that could have escalated towards armed conflict.
Furthermore, the question remains whether Russia, having an already imperial policy towards Ukraine, would be willing to potentially expose one of its few remaining allies to future dialogue over nuclear arms and proliferation control.
Already having an estimated 50 nuclear warheads, Kim Jong Un announced plans to aggressively expand Pyongyang’s arsenal in late 2023. In late November 2025, the Korea Institute for Defense Analyses (KIDA) delivered an assessment indicating that North Korea could now possess between 127 and 150 warheads.
If this pace continues, the DPRK could possess 200 nuclear missiles by 2030 and up to 400 by 2040.
North Korea’s rapid nuclear development stems from its expanding enrichment program and infrastructure, such as the Yongbyon facility. The DPRK positions its rocket force (KPASF) facilities along strategic missile belts – including one near China – to deter potential US strikes.
Fears of Russian technology in the hands of North Korea
Against the backdrop of Ukraine’s surprise offensive in Kursk, Kim Jong Un, who already supplies Russia with large quantities of artillery and missiles, deployed the North Korean Army (KPA) to help Russian forces regain the oblast. Approximately 10-12,000 KPA troops took part in combat against the Ukrainian Armed Forces, and several more advisers helped Russia demine the Kursk oblast.
North Korea suffered several thousand casualties but would not have committed some of their most elite troops unless Russia would return the favor. Along with gaining valuable combat experience and data, Pyongyang looks to procure and receive access to Russian technology, particularly for its nuclear submarine program.
In September 2025, Seoul’s military and National Intelligence Service (NIS) obtained intelligence that Russia possibly transferred two to three modules needed for Pyongyang’s nuclear submarines. If the module transfer is confirmed, North Korea will likely have a full functioning propulsion system and a compatible nuclear reactor.
38 North at the Stimson Center observed that the incorporation of Russian modules into the DPRK’s nuclear submarine program could increase pressure on South Korea and Japan to pursue nuclear-powered submarines.
In this context, Seoul’s cooperative relationship with the United States, including its role in revitalizing US shipbuilding, contributed to US President Donald Trump’s decision to authorize South Korea’s development of a nuclear submarine.
Genuine intermediary – or primarily buying time for North Korea?
The Lee administration is diverging from the more hawkish policies of the former Yoon administration.
After the failed coup, former Yoon has been on trial, in which prosecutors accused him of attempting to provoke an armed conflict with the DPRK. Lee now looks to avoid a conflict.
Lee is reaching out to Russia, akin to his outreach to the Trump administration, to bring Pyongyang back to the table over lowering its nuclear proliferation. The one question remains: can Moscow be trusted?
Russia’s war machine, now exhausted after several years of perpetual war in Ukraine, relies on North Korea’s armaments. The Russian Armed Forces needed KPA intervention to fully regain Kursk, despite their manpower advantage over Ukraine in this war.
Despite stating that there would be severe consequences for the KPA intervention and for growing cooperation with the Kremlin, South Korea has remained mostly idle. Seoul, to avoid inflaming tensions with Moscow, did not supply Kyiv with weapons and Lee wants to use Pyongyang’s allies as a conduit for future talks.
Russia’s war effort depends on DPRK military and supply support, making it unlikely that Putin will pressure Kim toward nuclear negotiations. Furthermore, Russia has possibly conducted informational warfare inside South Korea.
Posters enticing citizens of the Republic of Korea were plastered in Seongnam in November 2025, which is a hallmark of Russian disinformation to further decouple Ukraine’s support from international partners.
President Lee aims to maintain stability by using diplomatic back channels with rivals like Russia and China and by strengthening ties with the United States and other Indo-Pacific allies concerned about North Korea’s nuclear arsenal.
South Korea will also gauge the Kremlin’s response to outreach attempts, as Russia’s ongoing economic decline increases its dependence on support from the Kim regime.
Julian McBride is a defense analyst and contributing editor at 19FortyFive