TOKYO — North Korea claimed Friday that it successfully conducted a "higher level" test of a nuclear weapon, its second in eight months and its fifth since 2006. The announcement drew immediate condemnation from the United States, South Korea, China and Japan.
The U.N. Security Council scheduled an emergency meeting on the matter Friday, and President Obama warned North Korea that the United States would use "the full spectrum of U.S. defense capabilities" to defend its allies.
“To be clear, the United States does not, and never will, accept North Korea as a nuclear state,” Obama said.
The North Korean government in the capital of Pyongyang said the test was of a nuclear warhead designed to be mounted on ballistic rockets and demonstrated that it was prepared to hit back at its enemies including the United States if provoked. North Korea’s state TV said the test was "examined and confirmed." The announcement followed seismic activity near the country's nuclear site picked up by foreign monitors.
The test violaties United Nations resolutions and will further strain North Korea's already tense relations with the U.S. and other countries in the region.
China, an ally and economic lifeline for North Korea, was among the countries that swiftly reprimanded North Korea.
The White House said President Obama, who was enroute home from a summit in Laos, spoke by phone with South Korean President Park Geun-hye and Japanese Prime Minister Shinzo Abe. Obama said the allies agreed to agreed to work the UN Security Council and with China and Russia to impose new sanctions on North Korea. The U.S. will also deploy Terminal High Altitude Area Defense battery to South Korea, Obama said.
Park called the detonation an act of “fanatic recklessness.”
Tokyo Gov. Yuriko Koike told reporters the city was testing water samples and monitoring radiation levels to gauge any impact from the test in Japan.
Previous U.N. resolutions have forbidden North Korea from developing nuclear weapons or ballistic missile technology, but have had little effect. Seoul estimated that the test may be the North’s biggest explosive yield yet.
"We are monitoring and continuing to assess the situation in close coordination with our regional partners," said Ned Price, a spokesperson for the National Security Council in Washington, in a prepared statement.
Earlier, South Korea’s military detected a magnitude 5 earthquake near the Punggye-ri nuclear test site in northeastern North Korea. It described that quake as "artificial."
The test coincides with the 68th anniversary of the founding of the Democratic People’s Republic of Korea, as North Korea is known officially. In the past, the reclusive nation has marked major anniversaries with weapons tests or other provocative actions.
South Korean news agency Yonhap reported that the test is believed to have taken place in the same location where North Korea conducted its fourth nuclear test in January.
Pyongyang also conducted nuclear tests in 2006, 2009 and 2013.
While North Korea’s nuclear tests are “unwanted,” they are no longer de-stabilizing, said Robert E. Kelly, professor of political science at South Korea’s Pusan National University. “We've known for awhile that North Korea has functional nuclear weapons," he said.
"The real issues are can they improve these weapons from basic atomic bombs to hydrogen weapons? And can they marry them to a missile so that they can deliver them? The answer on both counts right now is probably 'No,'” Kelly said in email exchange Friday.
About 28,000 U.S. troops are stationed in South Korea, which technically remains at war with its neighbor to the north.
In January, North Korea conducted what it said was a test of a much more powerful hydrogen bomb, although the U.S. government disputed that claim. Since then the North has conducted several tests of medium and long-range missiles as part of its push for a nuclear-armed missile that could one day reach the U.S. mainland.
Earlier this week, North Korea fired three ballistic missiles into Japan’s exclusive economic zone in the Sea of Japan in an apparent signal of its displeasure with Group of 20 summit talks being held in Hangzhou, China.
Contributing: Oren Dorell in Washington, D.C.