The US Secretary of State Mike Pompeo warned Russia, China and other countries on any violations of international sanctions against North Korea, AP reported. 

According to him, the US has new, credible reports that Russia violates UN sanctions by allowing joint ventures with North Korean companies and issuing new permits for North Korean migrant workers.

He noted that Washington "takes seriously" any violations.

"If these reports prove accurate, and we have every reason to believe that they are, that would be in violation," Pompeo said, noting that the U.N. Security Council had voted unanimously in favor of the sanctions. "I want to remind every nation that has supported these resolutions that this is a serious issue and something we will discuss with Moscow. We expect the Russians and all countries to abide to the U.N. Security Council resolutions and enforce sanctions on North Korea.”

According to Pompeo, he is still optimistic that North Korean leader Kim Jong-un will fulfill his promise to the US President Donald Trump on denuclearization.