South Korean national security adviser Chang Ho-jin issued another stark warning Sunday, clarifying that South Korea will have no red lines left to uphold if Russia supplies "high-precision weapons" to North Korea, at a time when Seoul and Moscow are walking a tightrope in their relations.

"Russia's recent actions have been gradually approaching a red line, which is why we've issued the warning," Chang said Sunday during an interview with state broadcaster KBS, without specifying what constitutes the line.

Seoul and Moscow have been publicly exchanging warnings, each cautioning the other not to cross a red line, following the high-stakes summit between North Korean leader Kim Jong-un and Russian President Vladimir Putin on Wednesday during Putin's first trip to Pyongyang in 24 years.

The meeting revived mutual defense commitments similar to the level of their former Cold War-era 1961 treaty, including immediate military intervention. This has elevated military cooperation between the two nuclear-armed countries, both of which are under international sanctions, despite Seoul's public warnings against such actions.

"If (Russia) provides high-precision weapons to North Korea, then what lines will we have left to maintain?" Chang posed Sunday, directly addressing remarks made by Putin.

Putin on Thursday said that he would not rule out the possibility of providing North Korea with high-precision weapons as a countermeasure to US and EU military aid for Ukraine.

"I would like to point out that public opinion will likely reflect this sentiment, and Russia needs to take this aspect into consideration," Chang added.

During his interview with KBS, Chang also underscored, "The composition of our weapons support for Ukraine could change depending on how Russia responds in the future."

However, Chang declined to specify the types of weapons South Korea might provide to Ukraine, explaining that revealing such details "would weaken our leverage against North Korea and Russia."

"Managing South Korea-Russia relations is not something we can do alone. Russia also needs to make corresponding efforts," Chang emphasized.

"If Russia wants to restore and develop South Korea-Russia relations after the war (in Ukraine), I would like to stress once again that it needs to carefully consider its actions."

Chang's warning came just days after he announced Thursday that South Korea "plans to reconsider its stance on weapons support for Ukraine" in response to the signing of the Treaty on Comprehensive Strategic Partnership by Kim and Putin. His remark hinted at a potential shift from Seoul's long-held policy of refraining from providing lethal aid to Kyiv -- a move that Russia has indicated would be a red line.

In return, Putin on the same day warned that South Korea's possible deliveries of lethal weapons to Ukraine "would be a grave mistake," stating that Russia "will also make the necessary decisions that the leadership of South Korea will hardly welcome" if that happens.

The South Korean government also issued a statement to express "grave concern and condemn" the signing of the treaty that "aims to strengthen mutual military and economic cooperation" hours after North Korea unilaterally released the full statement of its treaty with Russia on Thursday morning.

The Institute for National Security Strategy, affiliated with Seoul's spy agency, underscored in a report released Friday that the South Korean government "should work to render the Russia-North Korea alliance treaty invalid in the medium to long term."

"If the Russia-Ukraine war ends and North Korea's strategic value decreases, or if South Korea-Russia relations gain importance, the treaty could be nullified," the institute said. "Thus, it is crucial to ensure that the provisions of the Russia-North Korea alliance treaty are not implemented in practice for the time being."

The controversy mainly revolves around clause 4 of the treaty, despite Chang's warning on June 16 that Russia should not "go beyond a certain point" just days before the summit.

The clause stipulates that North Korea and Russia "shall immediately provide military and other assistance using all means at their disposal ... if either party is subjected to military aggression from an individual country or multiple countries and enters a state of war."

Jeh Sung-hoon, a professor of Russian studies at Hankuk University of Foreign Studies in Seoul, commented, "The treaty appears to be at a level that can be considered an alliance treaty."

"According to the document, North Korean support troops could potentially appear on the Ukrainian front. Additionally, in the event of a war on the Korean Peninsula, Russia could provide weapons to North Korea in a manner similar to North Korea's support to it against Ukraine," Jeh told The Korea Herald.

Patricia Kim, a fellow at the Brookings Institution in Washington, also highlighted the security implications of the treaty, noting that the treaty's deliberately ambiguous language is intended to instill caution in the US and its allies.

"A grave concern is that with a Russian 'security guarantee' or at least the facade of one in hand, North Korea may be emboldened to intensify its provocations based on the calculation that the United States and its allies will respond with greater caution now that they have to take a potential Russian reaction into account," Kim said in a commentary issued Friday.

"Putin could very well welcome a North Korean provocation on the Korean Peninsula that forces the United States to turn its attention away from Europe, where Russia is continuing its relentless war against Ukraine," Kim added.