UN Security Council convened an emergency meeting on North Korea.

Continuing: Ministry of Defense of Russia estimated the power of nuclear bombs North Korea
SyuzhetyYadernoe Korei25.05.2009Severnaya disarming North Korea conducted a nuclear test and missile launches
   The representative of the Russian Federation to the UN Vitaly Churkin has convened an emergency meeting of the UN Security Council, which will be discussed by North Korea's May 25 nuclear tests. As reported by BBC News, the meeting scheduled for the evening of May 25.
In addition, Japanese authorities announced that a special working group to the Prime Minister of Japan. According to AFP, in South Korea to resolve the situation a "crisis team" of generals. Previously, it was reported that South Korean President Lee Myung Bak convened to discuss the actions the DPRK emergency meeting of the National Security Council.
RIA Novosti reported that Russian Defense Ministry has confirmed the information about the nuclear tests in North Korea. Details of the tests specified. The American military, according to BBC News, has not yet completed the verification of the message the DPRK. U.S. authorities, according to the AFP, have announced a major concern for the situation.
Early on the morning of May 25 Central News Agency of DPRK reported that the country held a successful underground nuclear test - more powerful than in 2006. According to South Korean media, the bombing was carried out in north-eastern town of Kilchzhu (ibid., where in 2006). In the area of the city of the U.S. Geological Survey recorded it "artificial" earthquake of magnitude 4.5, whose epicenter was at a depth of 10 kilometers.
Later, the media reported that in conjunction with underground tests of the DPRK launched a missile surface-to-air short-range actions.
North Korea first tested nuclear weapons in October 2006. In this regard, the UN imposed on the country a number of economic sanctions. Because of the difficult economic environment, the DPRK agreed to soon resume the six-party talks on nuclear disarmament. In the talks involved China, Japan, Russia, United States and South Korea. In April 2009 North Korea launched a missile with a satellite. UN Security Council condemned the launch, which the DPRK announced that out of the six-party talks and resuming its nuclear program.