UPDATED at 4:50 p.m. EST on 2016-01-06
North Korea said it successfully tested a hydrogen nuclear device on Wednesday, a fourth atomic bomb test by the isolated regime that drew widespread international condemnation, including from allies China and Russia.
The test, announced with bombast by North Korean state media but conducted without notifying ally China in advance, will be taken up on Wednesday in an emergency session by the UN Security Council, which has responded to the North's previous nuclear tests in 2006, 2009 and 2013 with a series of economic and trade sanctions.
"The successful H-bomb test was a measure for self-defense the DPRK took to protect its sovereignty and the vital rights of the Korean nation from the escalating nuclear threat and blackmail by the hostile forces, as part of its efforts to reliably defend the peace on the Korean Peninsula and regional security," said the official KCNA News Agency. It called the purported new weapon " "the H-bomb of justice."
In Seoul, local media quoted South Korean President Park Geun-Hye as telling an emergency National Security Council meeting that the test was "not only a grave provocation to our national security but also a threat to our future... and a strong challenge to international peace and stability."
China, for decades a close ally of North Korea, said it "firmly opposes" Pyongyang's actions.
"We strongly urge the DPRK side to remain committed to its denuclearization commitment, and stop taking any actions that would make the situation worse," foreign ministry spokeswoman Hua Chunying told a regular briefing in Beijing.
No acceptance as nuclear state
Japanese Prime Minister Shinzo Abe slammed what he called "a serious threat to the safety of our nation".
"This clearly violates UN Security Council resolutions and is a grave challenge against international efforts for non-proliferation," he said.
Without confirming the type of device North Korea set off, U.S. Secretary of State John Kerry condemned the test, which North Korea announced after international seismology monitors recorded a 5.1-magnitude tremor next to the North's main Punggye-ri nuclear test site.
"This highly provocative act poses a grave threat to international peace and security and blatantly violates multiple U.N. Security Council resolutions," he said in a statement.
"We do not and will not accept North Korea as a nuclear armed state, and actions such as this latest test only strengthen our resolve," added Kerry.
The foreign ministry of Russia, which as the Soviet Union installed the regime of current North Korean leader Kim Jong Un's grandfather in the late 1940s, condemned the test as "flagrant violation of international law and existing UN Security Council resolutions".
France and Britain joined its fellow permanent members of the UN Security Council in criticizing Pyongyang.
The claim of a successful hydrogen bomb test followed a comment last month by Kim suggesting Pyongyang had already developed a hydrogen bomb. Experts remained skeptical of the claim, which will require chemical testing to verify, because the magnitude of the blast on the Richter scale was not nearly as great as would be expected from a hydrogen bomb.
Kim's latest provocation is expected to cast a fresh spotlight on China's policies toward its problematic neighbor. Critics say that although China has evolved in the decade since Pyongyang's first nuclear test from defending the regime and blocking censure of its behavior to voting in support of UN sanctions, Beijing's enforcement of bans on trade remains spotty.
"Sanctions by the UN so far did little damage to Pyongyang’s economy thanks to Beijing’s massive material support through the backdoor," said Sung-yoon Lee of The Fletcher School of Law and Diplomacy at Tufts University in Massachusetts.
"For example, China’s supplies of food, fertilizer and heavy oil increased a year after North Korea was slapped with UN sanction for its first nuclear test in 2006. That was the same back in 2013, when the UN Security Council adopted a strong resolution condemning Pyongyang’s 3rd nuke test.”
Eyes on China, US
China remains North Korea's main source of aid, trade and investment, but relations have become strained in recent years, over the North's nuclear program and other mercurial behavior by Kim. Kim has yet to visit Beijing since coming to power four years ago and high-level visits and exchanges between the old Cold War allies have tapered off or been fraught with acrimony in recent years.
North Korea expert Andrei Lankov of Kookmin University in Seoul told RFA that Wednesday's test looked likely to undo any progress Beijing and Pyongyang had made to mend ties in 2015.
“Additional UN sanctions will be of little consequence to North Korea. As a matter of fact, one factor that the North dreads most at the moment is not UN sanctions but China’s attitude," he said.
"China enjoys a virtual monopoly on its trading with North Korea. Actually three quarters of N. Korea’s trade with outside world done is with China.”
Timothy Stafford, a research analyst on nuclear proliferation and policy at the Royal United Services Institute in London, said North Korea was challenging China's effort to balance concerns over Pyongyang's nuclear proliferation with its fear that pressure will bring down Kim's hereditary dictatorship and flood adjacent parts of China with destitute, hungry refugees.
"The Chinese will probably not push as hard as the Americans and the Europeans will," he told RFA's Korean Service. "They are worried not just about a strong North Korea, but also about a weak North Korea."
Stafford saw Kim's move as also directed at raising North Korea's profile in the United States, where foreign policy attention has largely been focused on the Middle East and Russia.
"North Korea wants to move itself up the agenda as more of a priority. The calculation in Pyongyang is that actions like these increase the chance of North Korea getting more from the United States," he added.
Reported by RFA's Korean Service. Written By Paul Eckert.