Japan’s top nuclear envoy on Thursday urged the UN Security Council to take appropriate action “sooner rather than later” over North Korea’s long-range rocket launch in December.

“We agreed that the Security Council, on behalf of the entire international community, must take appropriate action,” Shinsuke Sugiyama told reporters following a meeting with his South Korean counterpart, Lim Sung-nam, in Seoul.

“We are hopeful that the Security Council is responding in an appropriate manner sooner rather than later,” he said.

The US and its allies have been seeking tighter sanctions in the UN Security Council over what they believe are banned missile test in the guise of a long-range rocket launch. Pyongyang insists the launch was a purely scientific mission aimed at putting an observation satellite into orbit.

Japan and South Korea are considering independent sanctions on Pyongyang if China continues to block tougher measures on the Security Council, a policy Beijing argues would only further isolate North Korea.