Russia-South Korea standoff: Will the 'red lines' be crossed?

Lee Jong-eun

On June 19, Russia’s President Vladimir Putin traveled to North Korea for a one-day summit with the reclusive nation's leader Kim Jong-un. At the summit, the two leaders signed a comprehensive strategic partnership treaty, which included a clause committing the two countries to provide “immediate” military assistance if either side is in a state of war. After the summit, Putin expressed openness to advancing military and technical cooperation with the DPRK.

South Korea responded by warning that Russia’s sending sophisticated weapons or assisting the North’s nuclear and ballistic missile program would be crossing a “red line” for South Korea. South Korea’s National Security Adviser Chang Ho-jin warned that to counter Russia-North Korea military cooperation, South Korea would consider providing military aid directly to Ukraine. Putin, however, responded with his warning: South Korea would be making a “big mistake” by supplying weapons to Ukraine, motivating Russia to take actions unfavorable to the South Korean government.

Since then, a diplomatic stand-off has persisted between Russia and South Korea. So far, each side has refrained from taking the actions threatened by the other: Russia has not provided advanced military technology to North Korea, and South Korea has not supplied arms directly to Ukraine.

For Russia, providing advanced nuclear and missile technology to the North presents three key dilemmas. The first is the fairness of the exchange. Providing Russia’s sophisticated military technology in return for North Korea’s conventional, often low-quality arms may disproportionately benefit North Korea. The second dilemma concerns the reliability of the North as a strategic partner. Receiving advanced military technology might embolden the North to further destabilize Northeast Asia's geopolitical security without consulting Russia. Putin’s reluctance to describe the Russia-North Korean relationship as an “alliance” and his assertion that Russia will only defend the North in case of aggression against it might reflect Russia’s reservations about the Pyongyang’s unpredictable actions.

The third dilemma involves Russia’s relations with the strategically more important China. China might view Russia’s increased support for North Korea, especially in nuclear and missile development, as encouraging provocations that threaten regional stability and strengthen the rival U.S.-led alliance in Northeast Asia. China has, in fact, distanced itself from being described as part of a trilateral partnership with Russia and North Korea.

South Korea also faces risks in following through on its threat to supply weapons to Ukraine. Firstly, the South Korean government risks deteriorating its relationship further with Russia, with whom it has sought to build a strong economic partnership since the end of the Cold War. Secondly, the South Korean government risks exacerbating domestic political polarization. While the South Korean public has generally supported providing humanitarian aid to Ukraine, sending military assistance has been more controversial. Consequently, the Yoon government may face political opposition, with critics arguing that it jeopardizes South Korea’s security by excessively intervening in overseas conflicts.

Though Russia and South Korea have so far displayed caution in crossing each other’s red lines due to the risks accompanying such actions, a major challenge is that the two countries are more likely to cross the “orange line,” more limited actions that are still unfavorable to the other’s strategic interests. Prompted by urgent requests from the United States and Europe, South Korea may expand its indirect involvement in Ukraine’s and Europe’s security, such as exporting arms to countries providing direct military aid to Ukraine. Russia may enhance its cooperation with the North to upgrade Pyongyang's conventional military capabilities (such as munitions rockets, and drones), as this will benefit Russia by improving the quality of the North's conventional arms.

Russia and South Korea will likely face the dilemma of tolerating others' actions that fall short of explicitly violating the “red line” warning. Will Russia tolerate South Korea’s indirect involvement in the Russia-Ukraine War? Will South Korea tolerate Russia’s assistance upgrading the North’s conventional military capability? If either Russia or South Korea attempts retaliation against the other’s actions, it risks escalation of bilateral conflict. Mutual hostility and distrust may eventually motivate the two countries to risk direct confrontation in Europe and Northeast Asia.

For South Korea, the challenging decision lies in whether to counter all aspects of the Moscow-Pyongyang partnership, risking escalated conflict with Russia, or to tolerate a limited partnership, provided it doesn't involve nuclear collaboration. Each response has pros and cons, but South Korea risks greater strategic vulnerability from exchanging retaliation with Russia. While South Korea's direct military aid to Ukraine is unlikely to alter the dynamics of the Russia-Ukraine War significantly, Russia's advanced military and technological support to North Korea could considerably affect the nuclear balance and deterrence in Northeast Asia.

What should be South Korea’s response? South Korea should continue to warn Russia of the consequences of providing excessive military support to the North while reassuring South Korea’s intent to limit involvement in the Russia-Ukraine War. Additionally, South Korea should reach an implicit understanding with Russia that limited bilateral conflict is inevitable in the current geopolitical context. Just as South Korea cannot ignore its geopolitical ties with the West, Russia cannot refrain from leveraging its strategic partnership with North Korea. Paradoxically, maintaining mutual restraint to uphold the "red lines" may require tolerating "orange-level" tensions between Russia and South Korea.

Finally, the United States should support South Korea's efforts to apply credible pressures and reassurances on Russia. For the U.S. geopolitical strategy, preventing Russia’s advancement of the North's nuclear capability is of greater strategic importance than South Korea's direct arms supply to Ukraine. By supporting South Korea in maintaining mutual red lines with Russia, the U.S. achieves “sacrifice the skin, to preserve the bone” in containing the geopolitical challenges from revisionist states such as Russia and North Korea.

Lee Jong-eun is an assistant professor of political science at North Greenville University.