South Korea vows response to North Korea bolstering Putin’s forces: ‘We won’t sit idle’

South Korean president Yoon Suk Yeol has vowed he “won’t sit idle” over reports from his country’s spy agency and the US that North Korea has sent thousands of troops to Russia to bolster Vladimir Putin’s forces.

Speaking in Seoul after talks with visiting Polish president Andrzej Duda, Mr Yoon described the North Korean deployment as “a provocation that threatens global security beyond the Korean Peninsula and Europe”.

"We agreed that North Korea’s troop deployment to Russia, which is in direct violation of the UN charter and UN Security Council resolutions, is a provocation that threatens global security," Mr Yoon said after the summit. “South Korea won’t sit idle over this,” he said.

South Korea’s spy agency told legislators that North Korea has sent at least 3,000 troops so far but likely aims to send a total of 10,000 troops to Russia by the end of the year.

Putin, asked about reports that North Korea had sent thousands of troops to Russia at a summit on Thursday, said that it was Moscow's business how to implement a partnership treaty with Pyongyang. Putin did not deny that North Korean troops were currently in Russia.

He said it was not Russia's actions that had escalated the war in Ukraine, pointing to Western supplies of weapons to Kyiv.

Ukrainian president Volodymyr Zelensky said in a nightly address from Kyiv that he had seen reports of up to 12,000 North Korean troops prepared to enter Russia.

He urged Ukraine’s allies “not to shy away” from responding to the foreign bolstering of Putin’s forces, though he did not specify how he thought Kyiv’s partners should react.

US defence secretary Lloyd Austin confirmed on Wednesday that North Korean troops were in Russia, nearly a week after the first reports of the deployment emerged.

He described the possibility that the soldiers could fight against Ukraine as “very, very serious”, adding they would be a legitimate target for Ukraine.

While there have yet to be reports of the troops fighting against Ukrainians, General Kyrylo Budanov, Kyiv’s spy chief, claimed nearly 3,000 of the soldiers are due to be transferred to the Kursk region bordering Ukraine by the end of October.

Ukrainian forces launched a daring cross-border attack in that region in early August, where they have been fighting ever since.

Mr Yoon said South Korea will work with allies and partners to prepare counter-measures that could be rolled out in stages depending on the degree of military cooperation between Pyongyang and Moscow.

His office said earlier this week that South Korea is considering various diplomatic, economic and military options, including supplying Ukraine with both defensive and offensive weapons systems.

South Korea, a growing arms exporter, has provided humanitarian aid and other non-lethal support to Ukraine and supported US-led economic sanctions against Moscow.

But Seoul has not directly provided Ukraine with arms, citing a long-standing policy of not supplying weapons to countries actively engaged in conflict.

It comes as Russian forces in eastern Ukraine have made “significant tactical advances” in the past week, reportedly entering the city of Selydove in Donetsk region.

The city of a prewar population a little over 20,000 sits just 10 miles south of Pokrovsk, a larger city that is key to the defence of the wider region. The capture of Selydove could prove a key stepping stone to the seizure of Pokrovsk, though Russian forces have suffered significant losses during the months-long assault on the two cities.

“Russian advances into Selydove, as well as territorial gains to the south and north of the town, may soon cause Ukrainian troops to withdraw from the area to avoid being trapped within a collapsing pocket,” writes the Institute for the Study of War (ISW), a US-based think tank.

Ukraine’s General Staff said the most intense Russian assaults along the entire front line were currently taking place in the vicinity of Selydove, and that Russia used both fighter and bomber aircraft to support its attack there.

The General Staff did not say whether or not the Russians were in the town or if Ukrainian forces had fallen back.