Russian President Vladimir Putin and North Korean leader Kim Jong-un share a limousine ride in Pyongyang, North Korea. (Yonhap-Korean Central News Agency)

Russian President Vladimir Putin signing a defense treaty with North Korean leader Kim Jong-un has South Korea rethinking its stance on arming Ukraine.

Through nearly 2 1/2 years of Russia’s grinding war in Ukraine, Seoul has not strayed from its policy of “nonlethal aid only” to Kyiv over two administrations, both liberal and conservative.

That may change now that Putin has committed to fight on Kim’s side in the event of an invasion under the new military pact signed during the Russian president’s state visit to Pyongyang.

The pact’s terms unveiled by North Korean state media say that should either side be attacked, the other side “shall provide military and other assistance with all means in its possession without delay” -- which many interpret as a pledge of automatic mutual defense.

Seoul, which has kept up a balancing act between not provoking Russia and doing its part to stand with the democratic world, has a complex array of security interests to consider before it can flip its policy on Ukraine aid.

But Putin’s move in Pyongyang at least sets the stage for Seoul to expand its scope of support to Kyiv -- while hurdles, including an elusive political consensus at home, remain.

The Korea Herald asked political leaders and strategic experts about the shifting calculus as the country weighs its decision.

Seoul warns of U-turn on Ukraine aid

The bond between Putin and Kim has been building before Seoul’s eyes for some time before it culminated with the recent treaty.

In a reaction to the Pyongyang summit, the Yoon Suk Yeol administration has said it may walk back its policy of nonlethal aid only for Ukraine.

Yoon’s national security adviser Chang Ho-jin said after a National Security Council meeting on June 21 that the administration “plans on revisiting the issue of weapons aid to Ukraine.”

Two days later, he said that there was “no line South Korea could not cross if Russia were to hand North Korea advanced weapons.” “The level of military aid we offer to Ukraine will depend on how Russia behaves,” he stressed.

The ruling People Power Party says under the circumstances, Seoul is “forced” to push harder for Ukraine’s victory.

“In the face of the dangerous collusion between North Korea and Russia, which amounts to an existential threat to South Korea, we have no choice but to give lethal aid to Ukraine another thought.”

After Putin’s move, giving Ukraine weapons was “beginning to sound more convincing” for many in South Korea, according to ruling party Rep. Yu Yong-weon, who serves on the National Assembly national defense committee.

“Putin did not have to go so above and beyond to thank Kim Jong-un for helping his war efforts,” he told The Korea Herald. “It doesn’t have to be lethal weapons right away. We can upgrade the kinds of weapons we send to Ukraine step by step, starting with ‘less offensive’ ones, like portable air defense missiles.”

Making sense of Putin’s new boldness

The message the Russian president is sending to South Korea, by sealing what the North Korean leader called a “powerful alliance,” is clear, according to Yang Uk, a research fellow at the Asan Institute of Policy Studies in Seoul.

“Between the two Koreas, Putin has chosen -- resoundingly and unapologetically -- to side with the North,” Yang, who serves as an outside policy adviser to South Korea’s Joint Chiefs of Staff, told The Korea Herald.

“Even for Putin, this is fresh heights of boldness that to Seoul can only feel like a slap in the face,” he said.

With the pact consolidating military support between Russia and North Korea, Russia has signaled that it is prioritizing relations with North Korea at the cost of potentially upsetting the South, according to an analysis by the Sejong Institute, a think tank under Seoul’s Ministry of Foreign Affairs.

“Seoul-Moscow relations have deteriorated to a point where we may have to confront a Russia-aided North Korea if a war were to occur in the Korean Peninsula,” said the analysis published June 27.

From Seoul’s perspective, the whys of Putin overstepping his bounds at this point are less clear.

Prior to his Pyongyang trip, some government experts in Seoul said that post-Ukraine war calculations would prevent the Russian president from doing something that could undermine the country’s ties with South Korea.

“North Korea has been acting as a weapons factory for Russia. For a country at war that is entering its third year, there is nothing Russia could want more than a constant supply of weapons,” Nam Sung-wook, who served as the Institute for National Security Strategy director, told The Korea Herald.

Putin and Kim had only each other to count on amid their isolation, cut off from the West and in growing conflict with it, according to Rep. Kim Gunn, the former top nuclear envoy of Seoul.

“The Ukraine war rewrote the rules of the game. Russia is running out of artillery shells to hit Ukraine with, and North Korea is the only country in the world that is willing to provide them,” he told The Korea Herald.

What South Korean 155 mm rounds could mean

If willing, South Korea has the potential capacity to help Ukraine with the most requested pieces of weaponry in the war -- the North Atlantic Treaty Organization-standard 155 mm artillery shells.

South Korea has supplied the warring country with the 155 mm shells via the US, but not in the official domain.

One of the US senators who spoke with South Korea’s national defense chief, Shin Won-sik, at the Shangri-La Dialogue in Singapore earlier this month, told The Korea Herald on condition of anonymity that she thanked him for “the 155 rounds to Ukraine,” referring to 155 mm artillery shells South Korea is reported to have lent to the US last year.

“Of course we made sure to thank the minister on the fact that Korea sent the 155 rounds to Ukraine, and you know (Korea) being part of the international community in this way as a leader and not just as the single partner to the United States I think is very important,” she said.

An official with the Seoul Defense Ministry said that the talk of the artillery munitions came up at the meeting with the senators, and that the South Korean shells would give the US flexibility to send more to Ukraine.

“We are aware of export contracts between a South Korean company producing artillery shells and the US Department of Defense,” the official told The Korea Herald, in a rare acknowledgment.

“Because of the South Korean artillery shells, the US would have more in their reserves of shells to provide Ukraine with. The extra shells could give the US more flexibility in Ukraine assistance,” the official said.

Risks and hurdles facing Seoul

Putin sparked protests from some lawmakers with the Democratic Party of Korea -- namely Reps. Kim Byung-joo, Wi Sung-lac and Chung Dong-young -- who said in a joint statement Monday that North Korea and Russia closely aligning was “deeply worrying.”

The Democratic Party as a whole, however, remains vehemently opposed to going beyond humanitarian assistance.

Rep. Lee Jae-myung, the former opposition leader, said in June 21 remarks that it was up to the Korean people -- not the Yoon administration -- “to determine whether the proposal to provide weapons to Ukraine is actually in the benefit of this country.”

Domestic consensus, at the same time, remains to be reached.

One recent poll showed 55 percent of respondents saying they are opposed to giving lethal aid to Ukraine. Just 34 percent said they supported it, while 11 percent said they were unsure. The poll asked 1,007 South Koreans aged 18 and older through telephone interviews conducted June 24-26.

There are also concerns about depleting the country’s own stockpile of munitions that could be critical under a possible scenario of confrontation with North Korea.

Some reports suggest that South Korea, which is technically still at war, could face shortages in shells within a few weeks of a conventional conflict with North Korea.