The leaders of South Korea and Japan have repeated their calls for stronger action to punish North Korea over its nuclear ambitions including denying the country oil supplies.
The demand contradicted the stance of Russian President Vladimir Putin, who in a meeting with South Korean President Moon Jae-in dismissed sanctions as a solution to North Korea's nuclear and missile development.
Moon and Japanese Prime Minister Shinzo Abe agreed to cooperate on seeking tougher United Nations sanctions against North Korea, which conducted its sixth nuclear test on Sunday.
Pyongyang claimed the test was a detonation of a thermonuclear weapon built for missiles capable of reaching the US mainland.
Mr Moon and Mr Abe also pledged to strengthen efforts to persuade Beijing and Moscow into cutting off oil supplies to the North, said Yoon Young-chan, Mr Moon's chief press secretary.
Ahead of his meeting with the Japanese PM, Mr Moon said that the North's continuing weapons tests have created a "serious and urgent threat unseen before".
In his meeting with the Russian leader in the port city of Vladivostok, Mr Moon urged Moscow to support stronger sanctions against North Korea, but Mr Putin called for talks with North Korea, saying sanctions are not a solution to the country's nuclear and missile development.
The Russian president also expressed concern that cutting off oil supplies would hurt regular North Koreans, Mr Yoon said.
"We should not give in to emotions and push Pyongyang into a corner," Mr Putin said in a news conference, adding: "As never before, everyone should show restraint and refrain from steps leading to escalation and tensions."
Mr Abe, who is due to meet his Russian counterpart in Vladivostok on Thursday, said before his departure from Japan that "we must make North Korea understand there is no bright future for the country if it pursues the current path."