U.S. Secretary of State Mike Pompeo accused Russia on Friday of actively working to undermine international sanctions on North Korea and said the enforcement of the steps was essential to convince Pyongyang to give up its nuclear weapons.

“Russia has actively attempted to undermine the U.N. Security Council resolutions, the work of the … committee at the U.N. that evaluates compliance with sanctions,” Pompeo told a news briefing at the State Department.

Pompeo spoke after U.S. Ambassador to the United Nations Nikki Haley accused Moscow on Thursday of seeking to cover up breaches of U.N. sanctions on North Korea by Russians by pushing for changes to an independent report on sanctions violations.

Pompeo said he hoped the U.N. sanctions committee would “publish the original document that they intended to publish which shows clear activities related to sanctions and sanctions violations.”

“The United States is as committed as ever to continuing to enforce those U.N. Security Council resolutions. We believe they are central to President Trump’s efforts to convince Chairman Kim that full, final denuclearization of the Korean peninsula is necessary,” he said.

Pompeo added that the United States was continuing to have “many conversations” with the North Koreans about “how to effectuate achieving all of the commitments made” at a June 12 summit between Trump and Kim Jong Un, the North Korean leader.