Japan and the US early on Thursday confirmed to closely cooperate to cope with the hydrogen bomb test conducted by North Korea on Wednesday.

The international community needs to take a resolute action to send strong message to North Korea in order to prevent further provocations from the country, Japanese Prime Minister Shinzo Abe told US President Barack Obama in a phone conversation.

For his part, Obama said the nuke test was a threat to the region and the international community, and the US would take measures to ensure the security of its allies, including Japan.

Abe on Wednesday strongly condemned the hydrogen bomb test, saying the move was a "significant threat" to Japan's national security. Japan would consider further sanctions against the North Korea, Xinhua news agency reported.

After a magnitude-5.1 shallow-focus earthquake was detected on Wednesday in northeast part of North Korea, the country's official media made a special report and announced it had successfully conducted its first hydrogen bomb test.

The move prompted the United Nations Security Council to hold an emergency meeting over the issue and drew international criticism that the test jeopardized efforts to realize a denuclearised Korean Peninsula.