In a latest sign of military cooperation between North Korea and Russia, a senior Ukrainian police official Sergei Bolvinov said Wednesday that part of a weapon that Russia used to attack Ukraine had Korean writing on it.

“Russians continue to use weapons from North Korea in the Kharkiv region,” he said in a Facebook post, alongside a photograph of the wrecked weapon suspected of having been sourced from North Korea.

The National Intelligence Service in Seoul believes North Korea began delivering conventional weapons such as artillery shells to Russia by train in November 2022.

Following the meeting between Russia’s Defense Minister Sergei Shoigu and the North’s Kim in July 2023, North Korea has been shipping anti-aircraft, short-range missiles and other weapons via ships and planes, according to the NIS response submitted to the National Assembly last month.

But the weapons North Korea is sending to Russia are outdated and of low-quality, the NIS said. Still, Russia appears to be benefiting from the North Korea-supplied weapons, which are being delivered in large quantities, it added.

In return, Russia likely provided advice on North Korea’s launch of its first reconnaissance satellite in November 2023. The NIS suspects Russia could provide North Korea with key technologies for building strategic weapons and for modernizing conventional weapons.

On top of the weapons supply, North Korea has agreed to send more of its workers to Russia, which is suffering from labor shortages as a result of the war in Ukraine, in what would be a violation of relevant UN Security Council sanctions. The NIS estimates there are currently some 4,000 North Korean workers staying in Russia, stationed mostly in the far eastern regions of Primorsky and Sakhalin.

South Korea and Russia recently exchanged testy statements over the situation surrounding the war in Ukraine.

Ivan Zhelokhovtsev, director of the Russian Foreign Affairs Ministry’s first department of Asia, told an interview with Russian state-owned news agency RIA Novosty over the weekend that Seoul and Moscow were “now going through difficult times.”

He said that Seoul was “being forced to support the collective West in the hybrid war unleashed against Russia.”