SEOUL , South Korea ( CNN ) -- The U.N. Security Council called an emergency meeting Monday after world leaders reacted with outrage to North Korea 's latest nuclear test . This screen grab from North Korean television on April 9 shows leader Kim Jong Il in Pyongyang . North Korea earlier said it had tested the weapon in an underground explosion , provoking an angry response from the world 's governments . It had threatened to conduct the test if the U.N. Security Council did not apologize for imposing sanctions on North Korea after it tested a rocket April 5 . The secretive communist state also apparently test-fired a short-range missile Monday , the White House said . The Security Council called on its members to discuss the reported test Monday at 4 p.m . ET . Watch how the test may have taken world by surprise » . The United States and many other countries denounced the test . Even China , North Korea 's strongest ally , said it opposed the test . The White House -- which less than three weeks ago announced a new diplomatic effort to restart stalled talks with North Korea about its nuclear program -- said the test was in `` blatant defiance '' of the Security Council . `` North Korea is directly and recklessly challenging the international community , '' the White House said . `` The danger posed by North Korea 's threatening activities warrants action by the international community . '' While the test was not a surprise , Adm. Mike Mullen , chairman of the Joint Chiefs of Staff , said it showed Pyongyang was becoming `` increasingly belligerent . '' North Korea announced its underground nuclear test a little more than an hour after the U.S. Geological Survey reported a magnitude 4.7 seismic disturbance at the site of North Korea 's first nuclear test . There was no immediate information on the yield of the weapon used in Monday 's test . The Russian Defense Ministry said the explosion was between 10 to 20 kilotons . The U.S. State Department said it was analyzing the data . Mullen said it would take a couple of days to verify the reported test , but he added , `` there 's no indication that it was n't as they say . '' The North 's state-run Korean Central News Agency would say only that the latest test was safely conducted `` on a new higher level in terms of its explosive power and technology of its control . '' Watch more analysis on test » . U.S. intelligence estimated the first North Korean test , in October 2006 , produced an explosion equal to less than 1,000 tons of TNT . The low yield was a fraction of the size of the bombs the United States dropped on Japan at the end of World War II . Intelligence analysts had predicted North Korea would conduct a second rocket or nuclear test . The North threatened to do so after the Security Council voted unanimously to condemn its April launch as a violation of a 2006 resolution that bans North Korea 's ballistic missile activity . Watch how Pyongyang has used nuclear tests to gain concessions » . North Korea insisted the rocket was a communications satellite . It retaliated by threatening to walk away from the six-party talks aimed at disarming the country of nuclear weapons . The talks -- involving China , Japan , North Korea , Russia , South Korea and the United States -- are intended to persuade North Korea to scrap its nuclear program . The North also expelled international inspectors from its nuclear sites , announced plans to restart the reactor that produces plutonium for its nuclear weapons , and threatened to launch more rockets and another nuclear device . Monday 's test was conducted `` as part of the measures to bolster up its nuclear deterrent for self-defense in every way , '' the North Korean news agency said . `` They think this will enhance and embolden their diplomatic capability to deal with the other countries , '' said Han Sung Joo , former South Korean ambassador to the United States . `` Of course , it may be working the other way . But from their point of view , this is their lifeline , which they want to maintain . '' China 's government `` expresses firm opposition '' to the test , in which North Korea `` disregarded the opposition of the international community , '' according to a statement from China 's Ministry of Foreign Affairs . North Korea 's latest move could clear the way for the United States and the other members of the six-party talks , minus North Korea , to impose new punitive measures against a country desperate for food and energy assistance . For now , however , the North 's nuclear arms program is not a major security threat , analysts say . The country has yet to build an effective bomb or develop an effective delivery system to a target country . Watch South Korea 's reaction to the nuclear test » . Last year , North Korea acknowledged producing roughly 88 pounds ( 40 kilograms ) of enriched plutonium -- enough for about seven nuclear bombs . But analysts say North Korea is years from having a weapon it can put atop a long-range missile like those in the U.S. , Chinese or Russian arsenals . `` I know a lot of people may think , 'Oh no , a nuclear test . Does that mean war , conflict in the Korean Peninsula ? ' '' said Jim Walsh , an international security analyst at the Massachusetts Institute of Technology . `` The answer is 'no . ' '' CNN 's Sohn Jie-ae , Jaime Florcruz , Matthew Chance and Morgan Neill contributed to this report .
North Korea conducts second nuclear test , angering world governments . Emergency meeting of U.N. Security Council called . North also tested a short-range missile , White House says . U.S. says nuclear test was in `` blatant defiance '' of the Security Council .