Russia-N. Korea military cooperation 'significant security threat': S. Korea president

South Korea's president said Tuesday that growing military cooperation between Moscow and Pyongyang posed a major global security threat, after Washington accused North Korea of sending 10,000 soldiers to train in Russia.

"As the war in Ukraine continues for the third year, North Korea has gone beyond providing weapons to Russia and has even deployed troops," President Yoon Suk Yeol said.

Seoul's spy agency had previously said the North had sent thousands of soldiers, including elite special forces, to Russia, with Washington saying Monday that 10,000 were now training in the country.

"This illegal military cooperation between Russia and North Korea is a significant security threat to the international community and could pose a serious risk to our national security," President Yoon Suk Yeol said.

"We must thoroughly examine all possibilities and prepare countermeasures," Yoon said, adding that "measures would be actively taken step-by-step" depending on the progress of Russia-North Korea military cooperation, according to the presidential office.

That cooperation "fundamentally shakes the rules-based international order and threatens peace on the Korean Peninsula and globally", he added.

The North Korean foreign minister was headed to Moscow, Pyongyang's official Korean Central News Agency said Tuesday, without giving details.

South Korea, a major arms exporter, has previously said it would reconsider whether to supply weapons directly to Ukraine, something its Western allies have long called for. Seoul has so far resisted due to longstanding domestic policy.

Seoul has already sold billions of dollars of tanks, howitzers, attack aircraft and rocket launchers to Poland, a key ally of Kyiv.

In June, South Korea agreed to transfer the knowledge needed to build K2 tanks to Poland, which experts have said could be a key step towards production inside Ukraine.

In a Monday phone call with EU chief Ursula von der Leyen, Yoon described the current situation as "grave", warning that North Korean troops' entry into the front lines could "happen sooner than expected".

Ukraine said last week that North Korean soldiers had arrived in the "combat zone" in Russia's Kursk border region.

North Korea has denied sending troops to Russia, but in the first comment in state media last week, its vice foreign minister said that were such a deployment to happen, it would be in line with global norms.

"If there is such a thing that the world media is talking about, I think it will be an act conforming with the regulations of international law," said Kim Jong Gyu, North Korea's vice foreign minister in charge of Russian affairs.