South Korea has called on both Russia and North Korea to fulfill their duty not to exchange weapons.
South Korea's National Security Council said North Korea and Russia should comply with compliance with an arms trade ban and military cooperation, in accordance with U.N. Security Council resolutions and various international sanctions.
Seoul will firmly handle the issue of military cooperation between Pyongyang and Moscow in consultation with the United States, Japan and the international community, the council said.
The leader of South Korea's ruling party also denounced what he called the "devil's deal" between Moscow and Pyongyang, while Tokyo warned of any "violation" of UN Security Council sanctions on Pyongyang that prevent it from striking arms deals.
Japan's foreign minister said Tokyo was "following with concern" the talks between Moscow and Pyongyang, particularly in light of "the potential to lead to a violation of the UN Security Council embargo on any arms deal with North Korea."
There has been no official announcement of any agreement to deliver military equipment to Russia that could be used in its war on Ukraine.
North Korean leader Kim Jong Un arrived in Russia on Tuesday, his second visit since 2019, where he held a meeting with Russian President Vladimir Putin.
Washington's "hypocrisy"
In response to U.S. criticism of the summit meeting between Putin and Kim Jong-un, Russia said it was "hypocrisy," as Washington spread chaos and send weapons to its allies around the world.
Russia's ambassador to Washington said the United States had no right to give us lessons to teach us how to live.
The ambassador said Washington had formed an alliance in Asia, expanded military exercises near the Korean peninsula and supplied Ukraine with billions of dollars worth of weapons.