New York (CNN) Secretary of State Mike Pompeo's effort to marshal unified international pressure on North Korea, already under strain, showed cracks Thursday as Russia and China registered their opposition to further punishing Pyongyang.

Pompeo expressed frustration at a United Nations meeting Thursday that some countries were not strictly abiding by sanctions on Pyongyang, a major part of the US strategy to get North Korea to dismantle its nuclear and missile programs, along with President Donald Trump's efforts at personal diplomacy.

"It is imperative for members of the United Nations to take that to heart," Pompeo said of the need to maintain pressure. "Enforcement of UN Security Council sanctions must continue vigorously and without fail until we realize the fully, final, verified denuclearization. The members of this council must set the example on that effort, and we must all hold each other accountable."

'A wise decision'

But in the same meeting, the representatives from Russia and China pushed back on Pompeo, asking the US to make concessions or back off its push to maintain sanctions.

Read More