Pompeo, in a statement to the media, said that this punishment should not let up until North Korean leader Kim Jong-un keeps his promise to proceed toward denuclearization, Efe reported.

The United States government remains "optimistic" about the chances to make progress with North Korea, but believes that when sanctions are not adequately applied, the possibilities of success diminish, he said.

Pompeo met Friday in New York with South Korean Foreign Minister Kang Kyung-wha and with the Japanese ambassador before addressing a closed session of the Security Council.

The meeting was the first between Pompeo and the Security Council since US President Donald Trump's meeting in Singapore with North Korea's Kim.

Pompeo also informed the other powers about the results of his visit this month to Pyongyang.

"The UN Security Council is united on the need for final, fully verified denuclearization of North Korea as agreed to by Chairman Kim. Members of the UN Security Council and by extension all UN member-states have unanimously agreed to fully enforce sanctions on North Korea and we expect them to continue to honor those commitments," Pompeo told reporters.

"When sanctions are not enforced the prospects for the successful denuclearization of North Korea is diminished," he said.

The US reported last week to the UN that North Korea was violating the sanctions imposed on it, importing more petroleum products than the amount permitted by means of ship-to-ship transfers on the high seas.

For that reason, Washington asked the Security Council to order all sales of those products to Pyongyang stopped immediately, a request that for now has been blocked by Russia and China, which have asked for additional information before proceeding.