National Security Adviser Chang Ho-jin gives a briefing at the presidential office in Seoul on June 20, regarding the Treaty on Comprehensive Strategic Partnership signed between North Korean leader Kim Jong-un and Russian President Vladimir Putin in Pyongyang the previous day. Yonhap

South Korea will determine the extent of its arms supply to Ukraine based on Russia's stance toward its relations with North Korea, a presidential official said Friday.

National Security Adviser Chang Ho-jin said Thursday South Korea will review the possibility of supplying weapons to Ukraine after North Korean leader Kim Jong-un and Russian President Vladimir Putin signed a pact pledging mutual defense in the event of war.

In response, Putin warned South Korea would be making a "big mistake" if it decided to supply lethal weapons to Ukraine.

"There are various options for providing weapons, and our position on the recent developments between Russia and North Korea depends on how Russia approaches the situation going forward," the official said in a phone call with Yonhap News Agency.

South Korea has only supplied non-lethal items and equipment to Ukraine for its war against Russia under a policy that bans providing lethal weapons to countries at war.

Among potential weapons under consideration are 155-mm artillery shells, as well as air defense systems, which are needed in Ukraine, according to government sources.

Seoul officials have maintained strategic ambiguity regarding the types of weapons, seen as a diplomatic move to leverage the option to pressure Moscow to refrain from transferring key military technology to Pyongyang.

Later in the day, South Korea is expected to call in the top Russian envoy in Seoul to lodge a protest over the new treaty signed with North Korea, according diplomatic sources. (Yonhap)