Russian President Vladimir Putin attends a ceremony to receive credentials from newly arrived foreign ambassadors at the Alexander Hall of the Grand Kremlin Palace in Moscow, Dec. 4 (local time). AP-Yonhap

Relations between South Korea and Russia are expected to get stuck in limbo, with Moscow apparently criticizing Seoul's alleged indirect artillery ammunition support for Ukraine, while Seoul sees ongoing military cooperation between Russia and North Korea as an imminent national security threat.

Experts arrived at the predictions following Russian President Vladimir Putin's recent remark that normalizing bilateral ties depends on South Korea. This was interpreted as indirect pressure on Seoul to cease provision of military support to Ukraine.

According to Russian news agency TASS, Putin told the new South Korean Ambassador to Russia Lee Do-hoon that it "depends on Seoul" if South Korea-Russia cooperation returns to "the trajectory of partnership, so beneficial for our countries and peoples," during a credentials presentation ceremony on Monday.

Putin expressed regret for the broken relationship. "The relations between Russia and (South) Korea are unfortunately going through not the best period," he said, adding that he was ready to improve them.

The remarks came against a background of rising tensions between South Korea and Russia.

In the wake of the war between Russia and Ukraine, South Korean President Yoon Suk Yeol hinted at providing support other than humanitarian aid to Kyiv. Moscow responded with a summit between Putin and North Korean leader Kim Jong-un in Russia in September, which resulted in Pyongyang providing Moscow with ammunition.

South Korean government officials are saying it is providing humanitarian and financial aid to Ukraine and supplying non-lethal military items, such as helmets, first-aid kits and mine detectors. But international reports suggest Seoul has been providing indirect ammunition support by supplying the Americans with 155-millimeter shells to replace the munitions the U.S. is sending to support Ukraine's defense.

The Washington Post reported, Monday, that Seoul officials "were receptive as long as the provision was indirect" in U.S. requests for shells, and that South Korea has become "a larger supplier of artillery ammunition for Ukraine than all European nations combined."

155-millimeter artillery shells are packed for shipping at the Scranton Army Ammunition Plant in Scranton, Pennsylvania, Feb. 16. Reuters-Yonhap

Against that backdrop, Putin's remark is seen as a means of putting pressure on South Korea over the purported munition supplies.

"Though the shell supply may not be a decisive factor in the Ukraine war, it affects Russia's strategy of having a protracted war to make its enemy suffer supply drains," said Hong Min, a senior research fellow at the Korea Institute for National Unification.

"That means the implied message of Putin's remark is that Seoul is to blame for the frayed ties and it should stop listening to the U.S. and stop supplying shells to Ukraine."

More broadly, Hong said Putin's remarks appear to be targeting Seoul's efforts to expand its defense exports to countries close to western Russia, such as Poland.

"One of the most sensitive geopolitical risks that Putin sees is the North Atlantic Treaty Organization's expansion east, and Seoul appears to be playing a role in that by expanding its defense exports, which even include technology transfer," he said. "The most important background for Putin's remarks would be this."

Seoul did not offer a noteworthy response to Putin's, instead reiterating that "Our government maintains necessary communication with the Russian side for the sake of peace and stability on the Korean Peninsula, as well as for the protection of our citizens and companies on the territory of Russia."

South Korea's intelligence authority believes Russia has played a role in North Korea's recent launch of a military spy satellite — though it has yet to provide hard evidence for that. President Yoon has also stressed that Moscow-Pyongyang military cooperation is "a serious violation of United Nations Security Council resolutions and a major provocation threatening the peace of the Korean Peninsula, Northeast Asia and Europe."

"Seoul and Moscow both know that South Korea will not loosen its ties with the U.S., and Russia will not be proactive in containing North Korea's nuclear and missile programs, even if Seoul and Moscow mend their ties," Hong said. "For a while, the diplomatic relations between the two sides will likely be a buck-passing filled with diplomatic rhetoric blaming each other for the frayed ties."