Senior diplomats and defense officials of South Korea and the United States agreed on Friday that military cooperation between North Korea and Russia is a serious violation of U.N. sanctions and that the allies would ensure there is a price to pay.

The officials, meeting in Seoul to discuss "extended deterrence" against growing threats from North Korea, called on Moscow to show responsibility as a permanent member of the Security Council.

"We agreed to work together to ensure there is a price to pay for the grave violation of Security Council resolutions," South Korean Vice Foreign Minister Chang Ho-jin told a news conference.

North Korean leader Kim Jong Un is visiting Russia this week and met President Vladimir Putin to discuss military cooperation, the war in Ukraine and Russian help for North Korea's satellite program.

U.S. Under Secretary of Defense Sasha Baker said the allies will identify, expose and counter Russian attempts to acquire military equipment for the war in Ukraine.

U.S. and South Korean officials have expressed concern that the summit between the increasingly isolated Moscow and Pyongyang was aimed at allowing Russia to acquire ammunition from the North to supplement its dwindling stocks.

Chang and U.S. Under Secretary of State Bonnie Jenkins also said any use of nuclear arms by the North against the South would be met with a swift and overwhelming response.