Top nuclear envoys from South Korea, the U.S. and Japan have strongly denounced the expanding military cooperation between North Korea and Russia, which came after Russian President Vladimir Putin's visit to Pyongyang last week.

The condemnation came in a joint statement following phone talks on Monday between Vice Foreign Minister for Strategy and Intelligence Cho Koo-rae, U.S. Senior Official for the North Jung Pak and Japan's Assistant Foreign Minister for Asian and Oceanian Affairs Namazu Hiroyuki.

The envoys condemned "in the strongest possible terms" the deepening military cooperation between the North and Russia, adding that the North's arms transfers prolong the suffering of the Ukrainian people, violate multiple UN Security Council resolutions and threaten stability in both Northeast Asia and Europe.

They said the advancement of the Pyongyang-Moscow partnership, as highlighted by their comprehensive strategic partnership treaty, “should be of grave concern to anyone with an interest in maintaining peace and stability on the Korean Peninsula" and upholding the global nonproliferation regime.

The three sides reaffirmed their intention to further strengthen diplomatic and security cooperation to counter the North's security threats, while also urging the regime to cease further provocations and return to negotiations.