TOKYO (Sputnik) — North Korea claimed earlier in the day that it had successfully tested a hydrogen bomb that could be loaded on an intercontinental ballistic missile.
"This test surpasses all previous ones," Onodera said as quoted by the Nikkei newspaper.
South Korean media earlier suggested that an estimated capacity of North Korea's possible nuclear test may have reached 50 kilotonnes.
North Korea claimed that no radiation leak occurred during its test of a hydrogen bomb on Sunday, media reported. The Japanese NHK broadcaster also said that the test ended in no radiation leaks.
The Japanese government has condemned North Korea in the strongest terms through its embassy in Beijing and will coordinate its actions with the United States and South Korea to request the United Nations to convene an emergency Security Council meeting, Kono said as quoted by the NHK broadcaster.