The US, South Korea and Japan are pushing for a new multi-national panel of experts, possibly outside the UN, to ensure sanctions enforcement against North Korea after Russia and China thwarted monitoring activities at the world body, three sources said on Wednesday.

The push came after Russia rejected the annual renewal of the UN panel of experts that has over the past 15 years monitored the implementation of sanctions aimed at curbing North Korea’s nuclear and missile programmes. China abstained from the vote.

The envisioned new panel is aimed at continuing the UN entity’s work and would be operated by Washington, Seoul and Tokyo and joined by likeminded countries including Australia, New Zealand and some European countries, the sources said on condition of anonymity due to diplomatic sensitivity.

“The UN panel had faced some difficulties as Chinese and Russian members often tried to water down North Korea’s suspected sanctions evasion,” a senior South Korean government official said.

Such a team would likely lack the international legitimacy granted to a U.N.-backed operation, but would be able to more effectively monitor North Korea, the official said.

Seoul would prefer launching the mechanism among allies and friends, but there is a possibility that they will seek formal endorsement through the UN General Assembly (UNGA), another senior official said.

The team might also be mandated to monitor the implementation of resolutions on North Korea’s human rights situation adopted by the Security Council, the UNGA and the UN Human Rights Council, a third source said.

US ambassador to the United Nations Linda Thomas-Greenfield, when asked on Wednesday about creating a new panel of experts, said she would engage with South Korea and Japan to “develop options both inside and outside the UN.”

“The point here is that we cannot allow the work that the panel of experts were doing to lapse,” she told a news conference in Seoul.

Moscow and Beijing have called for sanctions on North Korea to be reduced as a way to jumpstart diplomatic negotiations and ease humanitarian suffering in the impoverished nation.

Thomas-Greenfield, visiting the heavily armed Korean border on Tuesday, urged Russia and China to reverse course, and stop rewarding North Korea’s bad behaviour and shielding it from sanctions evading activities.