Russia’s signing of a mutual defense agreement with North Korea last week brings Moscow closer to crossing South Korea’s “red line,” Seoul’s national security adviser stated Sunday.

“Russia is drawing closer and closer to our red line ... Moscow will need to deeply reconsider the matter should it desire to reinstate and develop the ROK-Russia relations after the [Ukraine] war,” Chang Ho-jin, the director of South Korea’s National Security Office, said in a live interview with KBS.