TOKYO - Japan and the United States confirmed early Thursday to closely cooperate to cope with the hydrogen bomb test conducted by the Democratic People's Republic of Korea (DPRK) in the previous day.

Japanese Prime Minister Shinzo Abe told US President Barack Obama in a phone conversation Thursday morning that the international community has to take resolute action to send strong message to the DPRK in order to prevent further provocations from the country, local reports cited a government official here as saying.

For his part, Obama said the nuke test is a threat to the region and the international community, and the United States 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 DPRK.

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

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 denuclearized Korean Peninsula.