North Korea says it has successfully test-fired an intercontinental ballistic missile (ICBM) for the first time, which it claims could reach anywhere in the world .
Experts, however, believe it could reach Alaska, but not the lower 48 US states or Hawaii.
Russia and China both share a land border with North Korea and have been involved in past efforts to try to calm tensions between Pyongyang and the West.
Russia and China have joined diplomatic forces and called on North Korea, South Korea and the United States to sign up to a Chinese de-escalation plan designed to defuse tensions around Pyongyang's missile program.
The plan would see North Korea suspend its ballistic missile program and the United States and South Korea simultaneously call a moratorium on large-scale missile exercises, both moves aimed at paving the way for multilateral talks.
The initiative was set out in a joint statement from the Russian and Chinese foreign ministries issued shortly after President Vladimir Putin and Chinese President Xi Jinping held wide-ranging talks in the Kremlin.
"The situation in the region affects the national interests of both countries," the joint statement said. "Russia and China will work in close coordination to advance a solution to the complex problem of the Korean Peninsula in every possible way."
Moscow and Beijing used the same joint declaration to call on Washington to immediately halt deployment of its THAAD anti-missile system in South Korea, a move Washington says is necessitated by the North Korean missile threat.
The statement said Washington was using North Korea as a pretext to expand its military infrastructure in Asia and risked upsetting the strategic balance of power in the area.
"The deployment ... of THAAD will cause serious harm to the strategic security interests of regional states, including Russia and China," the statement said.
"Russia and China oppose the deployment of such systems and call on the relevant countries to immediately halt and cancel the process of deployment."