Ministry of Defense of Russia estimated the power of nuclear bombs North Korea.

According to the Ministry of Defense RF power tested on 25 May North Korea nuclear device was 10 to 20 kilotons, reports RIA Novosti. An underground explosion in the DPRK has been reported by the special control of the Ministry of Defense of Russia in 4:54 Moscow time.
The test was conducted in 80 kilometers from the city Kilchzhu in the northern part of the country. In the area of the explosion has been recorded "artificial" earthquake of magnitude 4.5. According to the United States Geological Survey (USGS), the epicenter of the earthquake was at a depth of ten kilometers.
Shortly after Pyongyang's test confirmed the success of the underground nuclear explosion.
A little later, on 25 May with the launch complex Musudan (Musudan-ri) in the North Korean missile launch by an earth-to-air short-range actions.
In response to DPRK's nuclear test at 16:00 hours on 25 May (0:00 pm May 26, Moscow time) scheduled an emergency meeting of the UN Security Council. As the press-secretary of the Japanese Government, Takeo Kawamura, Japan will have to take at a meeting of a new resolution against North Korea.
Ministry of Foreign Affairs expressed concern over the DPRK's test, but stressed that the information should be carefully checked. Currently, a special service control of RF Ministry of Defense continues to monitor the situation on the territory of the DPRK.