Japanese Prime Minister Shinzo Abe on Saturday called North Korea's test-fire of a ballistic missile "absolutely unacceptable" and a "grave threat to our country".
Speaking in London, Abe called upon the international community, in particular China, to "show solidarity" in formulating a response.
"There is a major crisis looming over the peace and prosperity of the world," he told reporters at the end of a three-day visit to Russia and Britain.
"Despite strong warnings by the international community, North Korea today went through with its ballistic missile launch.
"It is a grave threat to our country, this is absolutely not acceptable, we strongly condemn such acts.
"Our country will be resolute in our response," he vowed.
North Korea test-fired the missile Saturday in apparent defiance of a concerted US push for tougher international sanctions to curb Pyongyang's nuclear weapons ambitions.
The latest launch, which South Korea said was a failure, came just hours after US Secretary of State Rex Tillerson warned the UN Security Council of "catastrophic consequences" if the international community -- most notably China -- failed to pressure the North into abandoning its weapons programme.
Abe said G7 leaders meeting in Italy next month, "shoulder a huge responsibility" in responding to the threat.
"The international community must display solidarity," he said, adding that he had agreed with Russia President Vladimir Putin on Thursday that Russia, China, Japan, US and South Korea all needed to cooperate closely on the issue.
He singled out China as being "extremely important" in resolving the crisis given its UN Security Council role and that it accounts for 90 percent of North Korea's trade.
"For the denuclearisation of North Korea, I hope China will play a constructive role in the implementation of UN Security Council resolutions. It is my high expectation that China will perform its role properly."