North Korea conducted its fifth and biggest nuclear test on Friday and said it had mastered the ability to mount a warhead on a ballistic missile, ratcheting up a threat that rivals and the United Nations have been powerless to contain.
The blast, on the 68th anniversary of North Korea's founding, drew a fresh wave of global condemnation. The United States said it would work with partners to impose new sanctions, and called on China to use its influence - as North Korea's main ally - to pressure Pyongyang to end its nuclear programme.
Under 32-year-old third-generation leader Kim Jong Un, North Korea has sped up development of its nuclear and missile programmes, despite U.N. sanctions that were tightened in March and have further isolated the impoverished country.
The United Nations Security Council denounced North Korea's decision to carry out the test and said it would begin work immediately on a resolution. The United States, Britain and France pushed for the 15-member body to impose new sanctions.
U.N. Secretary General Ban Ki-Moon urged the group to remain united and take action that would "urgently break this accelerating spiral of escalation."
U.S. President Barack Obama said after speaking by telephone with South Korean President Park Geun-hye and with Japanese Prime Minister Shinzo Abe that they had agreed to work with the Security Council and other powers to vigorously enforce existing measures against North Korea and to take "additional significant steps, including new sanctions."
LAVROV SEEKS NEW TALKS
But Russian Foreign Minister Sergei Lavrov said it may take more than additional sanctions to resolve the crisis. That diverged from calls by the United States, Japan and South Korea to escalate pressure on the North, signalling it may prove a challenge for the Security Council to come to an agreement on new sanctions.
"The current situation shows that diplomats should be more creative than just responding by sanctions, sanctions and sanctions again on any aggravation of the situation," Lavrov told a news conference in Geneva. "It is too early to bury the six-party talks. We should look for ways that would allow us to resume them."
The so-called six-party talks aimed at ending the North's nuclear programme involving the United States, Russia, Japan, South Korea, China, and North Korea have been defunct since 2008.
U.S. Secretary of State John Kerry said the United States had repeatedly offered talks to North Korea, but Pyongyang had to accept de-nuclearisation, which it had refused to do.
"We have made overture after overture to the dictator of North Korea," he said, adding that he ultimately hoped for a similar outcome as in the nuclear talks in Iran.
China said it was resolutely opposed to the test but Chinese Foreign Ministry spokeswoman Hua Chunying would not be drawn on whether China would support tougher sanctions against its neighbour.
On Saturday, the influential Chinese state-run tabloid the Global Times said North Korea was wrong in thinking building nuclear weapons would provide it more security or prestige in the world. "Owning nuclear weapons won't ensure North Korea's political security," it said in an editorial. "On the contrary, it is poison that is slowly suffocating the country."
Beijing has also repeatedly expressed anger since the United States and South Korea decided in July to deploy the Terminal High Altitude Area Defense (THAAD) anti-missile system in the South. China says that THAAD is a threat to its own security and will do nothing to bring North Korea back to the negotiating table on its nuclear programme.
"Washington and Seoul, in particular, should sincerely rethink their decision to install THAAD on the peninsula and review their other strategic mistakes that have prompted Pyongyang to make the wrong steps," Wang Junsheng, a researcher in Asia Pacific strategy at the government think tank, the Chinese Academy of Social Sciences, told the official China Daily in a piece published on Saturday.
Still, U.S. Defense Secretary Ash Carter singled out the role he said China should play. "It's China's responsibility," he told a news conference during a visit to Norway. "China has and shares an important responsibility for this development and has an important responsibility to reverse it."
"OUT OF CONTROL"
South Korea's Park said late on Friday Kim was "mentally out of control," blind to all warnings from the world and neighbours as he sought to maintain power. "The patience of the international community has come to the limit," she said.
North Korea, which labels the South and the United States as its main enemies, said its "scientists and technicians carried out a nuclear explosion test for the judgement of the power of a nuclear warhead," according to its official KCNA news agency.
It said the test proved North Korea was capable of mounting a nuclear warhead on a medium-range ballistic missile, which it last tested on Monday when Obama and other world leaders were gathered in China for a G20 summit.
Pyongyang's claims of being able to miniaturise a nuclear warhead have never been independently verified.
Its continued testing in defiance of sanctions presents a challenge to Obama in the final months of his presidency and could become a factor in the U.S. presidential election in November, and a headache to be inherited by whoever wins.
"Sanctions have already been imposed on almost everything possible, so the policy is at an impasse," said Tadashi Kimiya, a University of Tokyo professor specialising in Korean issues.
"In reality, the means by which the United States, South Korea and Japan can put pressure on North Korea have reached their limits," he said.
UNPRECEDENTED RATE
North Korea has been testing different types of missiles at an unprecedented rate this year, and the capability to mount a nuclear warhead on a missile is especially worrisome for its neighbours South Korea and Japan.
The Pentagon did not have evidence that North Korea had been able to miniaturise a nuclear weapon, Pentagon spokesman Gary Ross said. But he added, "given the consequences of getting it wrong, it is prudent for a military planner to plan for the worst."
It was not clear whether Pyongyang had notified Beijing or Moscow of its planned nuclear test. Senior officials from Pyongyang were in both capitals this week.
Preliminary data collected by the Vienna-based Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), which monitors nuclear tests around the world, indicated the magnitude - around 5 - of the seismic event detected in North Korea on Friday was greater than a previous one in January.
Jeffrey Lewis of the California-based Middlebury Institute of International Studies said the highest estimates of seismic magnitude suggested this was North Korea's most powerful nuclear test so far.
He said the seismic magnitude and surface level indicated a blast with a 20- to 30-kilotonne yield or its largest to date. Such a yield would make this test larger than the nuclear bomb dropped by the United States on the Japanese city of Hiroshima in World War Two, which exploded with an energy of about 15 kilo tonnes.
South Korea's military put the force of the blast at 10 kilo tonnes, which would still be the North's most powerful nuclear blast to date.
"The important thing is, that five tests in, they now have a lot of nuclear test experience. They aren't a backwards state any more," Lewis said.
