Japan today confirmed that North Korea has conducted a sixth nuclear test, a move the United States and its allies in the region are likely to view as a major provocation. <br/><br/>Two tremors struck North Korea today, suggesting the reclusive country may have conducted a nuclear test. <br/><br/>Seismological data from the United States Geological Survey showed that an explosion caused a 6.3-magnitude tremor in the country's northeast, where North Korea has detonated nuclear explosions in the past. China and South Korea said they also detected a second quake of 4.6 magnitude in North Korea. <br/><br/>Japan lodged a formal protest with Pyongyang after a major explosion at the isolated nation's main test site. Japanese Prime Minister Shinzo Abe said, a sixth nuclear test by Pyongyang is absolutely unacceptable and could not be tolerated. <br/><br/>Talking to reporters in Tokyo, Japanese foreign minister Taro Kono said, after examining information from the weather agency and other information, Japan government concludes that North Korea conducted a nuclear test. <br/><br/>He said, the government registered a protest with the North Korean embassy in Beijing prior to the confirmation, calling any test extremely unforgivable. <br/><br/>South Korea's military also said the first earthquake appeared to be manmade. National news agency Yonhap said a meeting of Seoul's National Security Council has been convened. The tremors came hours after North Korean leader Kim Jong-un was pictured with, what state media termed as a new type of hydrogen bomb.