NATO’s Rutte warns of a “serious escalation” if North Korean troops reinforce Russia’s invasion force in Ukraine, given it raises the risk of further third parties also committing troops to the conflict.

The will-they-won’t-they drama of the deployment of North Korean soldiers to the Ukraine War, boosting the Russian offensive effort, continues with new claims about the strength of the force and warnings from NATO. The new Secretary General of the North Atlantic Treaty Organisation Mark Rutte spoke with South Korean President Yoon Suk Yeol on Monday morning, the former Dutch Prime Minister reportedly telling the Korean a Pyongyang deployment would violate the sanctions regime.

Writing after the call, Rutte said: “I spoke with [President Yoon] about NATO’s close partnership [with] Seoul, defence industrial cooperation, and the interconnected security of the Euro-Atlantic and Indo-Pacific. North Korea sending troops to fight alongside Russia in Ukraine would mark a significant escalation.”

Seoul’s Vice Foreign Minister Kim Hong-kyun also spoke of the breaking of United Nations resolutions by the North Korean deployment, and said it posed a threat to security domestically and abroad. He said on Monday after the Rutte-Yoon call: “We condemn North Korea’s illegal military cooperation, including its dispatch of troops to Russia… We will respond jointly with the international community by mobilizing all available means against acts that threaten our core security interests.”

While the presence of North Korean troops in strength in Russia, Ukraine, or both has been widely discussed as a possibility or a reality for weeks now, it is only in the past few days these reports have coalesced into more solid claims. Even so, the exact composition of the force remains debated, with 1,500 troops discussed as training in Russia and an eventual possible force of 10,000 or 12,000.

The 12,000 figure, or four full brigades of infantry, is claimed by South Korea, reports Germany’s NTV. Part of today’s discussions has been NATO requesting a South Korean delegation travel to Europe to help on the intelligence picture regarding the North Korean brigades. Seoul said they would send the requested delegation quickly, and that they had summoned the Russian ambassador to demand the immediate withdrawal of North Korean troops.

Russia for their part remain typically circumspect, neither truly denying or confirming the North Korean troops claims. Government spokesman Dmitry Peskov said on Monday that: “North Korea is our close neighbor and partner and we develop relations in all areas and it’s our sovereign right. We will continue developing this cooperation further”.

It was definitely asserted last week that North Korean troops had arrived in Ukraine, and had even engaged in combat. President Volodymyr Zelensky said at first that “We see the alliance between [Russia] and such regimes as North Korea becoming stronger, and is no longer simply the transfer of weapons, it is about the transfer of people from North Korea to the military forces of the occupier”. Later be buttressed his remarks, adding on Friday: “If the world now remains silent and we on the front lines are confronted with North Korean soldiers as regularly as we defend ourselves against drones, it will not help anyone in this world and will only prolong this war”.

South Korea themselves provided intelligence over the weekend that North Korean troops had definitely become involved, releasing a video allegedly showing Pyongyang soldiers being issued with Russian military kit.