Russian President Vladimir Putin (R) and North Korean leader Kim Jong Un walk during a farewell ceremony upon Putin's departure at the Sunan International Airport in Pyongyang, North Korea, 19 June 2024. Russian President Vladimir Putin is on his two days official visit to North Korea. EPA-EFE/GAVRIIL GRIGOROV / SPUTNIK / KREMLIN POOL 
First vice foreign minister Kim Hong-kyun conveyed Seoul's stance on the pact and military cooperation between Russia and North Korea to Georgy Zinoviev, the top Russian envoy to Seoul, Seoul's foreign ministry said.
Kim told Zinoviev that Russia's military support for North Korea harms South Korea's security and would inevitably have a "negative impact" on relations between Seoul and Moscow.
He also urged Russia to "act responsibly," according to the ministry.
Attempts to intimidate Russia are unacceptable, Zinoviev was quoted as saying by the Russian Embassy in Seoul.
"The ambassador said that cooperation between Russia and North Korea is not aimed at a third country," the embassy said in a post on X soon after he was summoned to the ministry.
South Korea's foreign minister, Cho Tae-yul, and U.S. Secretary of State Antony Blinken have condemned the treaty as a serious threat to regional peace and stability, Seoul's foreign ministry said in a statement on Friday.
The two in a phone call on Thursday also discussed ways to respond to the summit between Putin and North Korean leader Kim Jong Un and agreed to closely monitor the situation, the foreign ministry said.
Blinken said the United States supports South Korea's responses to security threats. Under the pact, Moscow and Pyongyang said each country would provide immediate military assistance if either faces armed aggression.
Cho said any cooperation to help strengthen North Korea's military capabilities is a clear violation of the U.N. Security Council resolutions, according to the statement.
The United States will consider various ways to respond to the threat to international peace and stability from Russia and North Korea, Blinken was quoted as saying by the ministry.
Cho also spoke on the phone with Japanese Foreign Minister Yoko Kamikawa, and both expressed grave concern over the treaty between Moscow and Pyongyang, according to the ministry.
South Korean National Security Adviser Chang Ho-jin said on Thursday that Seoul would review the possibility of supplying weapons to Ukraine in response to the landmark pact.
Domestic ammunition manufacturer Poongsan Corporation gained 3.42% when the market closed on Friday, compared with a 0.83% drop in themain KOSPI .KS11.
(Reporting by Hyunsu Yim; Editing by Sonali Paul and Gerry Doyle)