South Korea's intelligence service announced on Sunday that it was investigating suspicions that North Korea was supplying Russia with weapons manufactured in the 1970s, which are allegedly being used by Moscow in its conflict with Ukraine.

The National Intelligence Service's response came after a recent report by a Ukrainian media outlet claimed that 122-millimeter artillery shells produced in North Korea in the 1970s were being used by Russia in the Ukraine conflict.

According to Yonhap News Agency, the South Korean intelligence service stated that it is carefully analyzing the situation and monitoring the extensive military cooperation between North Korea and Russia.

Photographs released by a Ukrainian photographer last year showed Korean characters, including "방-122," engraved on rocket shells, believed to be from a 122 mm multiple rocket launcher.

In mid-October, Washington reported that Pyongyang had shipped over a thousand containers of military equipment and ammunition to Russia. The following month, Seoul accused Pyongyang of sending over a million artillery shells to Russia, allegedly receiving technical advice on launching a military reconnaissance satellite in return.

In February, South Korean Defense Minister Shin Won-sik estimated that North Korea had sent around 6,700 containers to Russia since the summit between Kim Jong Un and Vladimir Putin in September the previous year. This quantity could hold approximately 3 million 152-caliber bullets or 500,000 122-caliber artillery shells.