North Korean shock troops in Ukraine? South Korea summons Russian ambassador over reports.

South Korea's foreign ministry called the Russian ambassador to the carpet Monday over North Korea's alleged deployments of troops to join the Russian military in its war against Ukraine.

The use of North Korean troops in the Ukraine conflict is a violation of the U.N. charter and General Assembly resolutions and threatens South Korea's security, the ministry said in a statement.

"We condemn North Korea's illegal military cooperation, including its dispatch of troops to Russia, in the strongest terms," Vice Foreign Minister Kim Hong-kyun told Ambassador Georgy Zinoviev, the ministry said. "We will respond jointly with the international community by mobilising all available means against acts that threaten our core security interests."

Zinoviev countered that Russian cooperation with North Korea was in line with international law, and was not directed against South Korea, according to a Facebook post from the Russian embassy.

Reports that Russia will deploy North Korean troops in its war with Ukraine are unconfirmed. The Kremlin earlier denied them.

South Korea's intelligence service said on Friday that North Korea had shipped 1,500 special forces to train at Russian military bases in the Far East. The troops would likely be deployed to fight in Ukraine, the spy agency said.

The agency said it had worked with Ukraine's spies and used facial recognition technology and artificial intelligence to identify North Korean military officers alongside Russian forces in the Donetsk region of eastern Ukraine.

Ukrainian President Volodymyr Zelenskyy has also accused North Korea of sending 10,000 troops to Russia.

South Korea's defense ministry said it had consulted with the U.S. on Monday. The White House National Security Council said it couldn't confirm the reports, but added it "would mark a dangerous development" in the war, according to a spokesperson.

Mark Rutte, the Secretary-General of NATO, said on X that he spoke with South Korean President Yoon Suk Yeol. North Korea sending troops to the conflict "would mark a significant escalation," he wrote.

Contributing: Reuters

This article originally appeared on USA TODAY: South Korea demands North Korea withdraw troops allegedly in Russia