North Korea's claim that it had successfully detonated a hydrogen bomb on Wednesday elicited an angry if familiar chorus of condemnation around the world. But Washington and the international community may yet again find it hard to muster the will to strengthen sanctions or take bold steps to lure North Korea back to the bargaining table anytime soon.
The United Nations Security Council condemned the Pyongyang government's assertion that it had exploded a "miniature" hydrogen bomb, calling it a "clear violation of council resolutions." In a statement issued after emergency consultations Wednesday, the council said it had previously expressed its determination to take "further significant measures" in the event of another North Korean nuclear test and would begin work immediately on a new resolution.
Successive rounds of U.N. sanctions have not persuaded the government of Kim Jong Un to rein in its nuclear weapons and ballistic missiles programs, however, and the council did not specify what new measures would be considered.
Aides to President Obama said that military options remained on the table if North Korea continues to pursue nuclear weapons but added that the president is currently focused on diplomatic responses.
"North Korea continues to be one of the most isolated nations in the world, and their isolation has only deepened as they have sought to engage in increasingly provocative acts," White House Press Secretary Josh Earnest told reporters.
Further condemnation came from South Korea, Japan, China and Russia, along with various arms control organizations.
If confirmed, the detonation would be North Korea's fourth nuclear test since 2006 but the first using fusion technology. North Korea's nuclear tests in 2006, 2009 and 2013 are all believed to have used plutonium-based, or perhaps uranium-based, atomic weapons.
The U.S. government's initial analysis of underground activity in North Korea was "not consistent" with the country's claim of having used a hydrogen bomb Wednesday, Earnest said.
Hydrogen bombs, also called thermonuclear bombs, can potentially be much larger than atomic weapons, which rely on fission for their explosive power. However, the initial data indicated the blast was not substantially larger than the country's 2013 test, said Daryl Kimball, executive director of the Washington-based Arms Control Assn.
"If indeed it was a nuclear test, whether H-bomb or A-bomb, we can expect another round of largely symbolic sanctions against North Korea, plus public condemnation from China," said Denny Roy of the East-West Center in Honolulu.
"I don't expect that this will fundamentally change South Korean, Chinese or U.S. policy toward North Korea," he added. "Beijing concluded long ago that the only thing worse than putting up with North Korea's bad behavior is the danger of a collapse of the Kim regime."
Secretary of State John F. Kerry said the U.S. was committed to defending the American people and honoring its security commitments to allies in the region.
"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," he said in a statement.
Defense Secretary Ashton Carter spoke by phone Wednesday with Gen. Curtis Scaparrotti, commander of U.S. forces in South Korea, and South Korean Defense Minister Han Min-koo to discuss the North's apparent nuclear test.
"Secretary Carter and Minister Han agreed that any such test would be an unacceptable and irresponsible provocation and is both a flagrant violation of international law and a threat to the peace and stability of the Korean peninsula and the entire Asia-Pacific region," Pentagon spokesman Peter Cook said in a statement.
Carter and Han agreed that the provocations should have consequences, Cook said, but he did not disclose what those consequences might entail.
U.N. diplomats told reporters that a new resolution could add more people to the sanctions list. How robust the measures will be will depend largely on China, North Korea's traditional ally on the Security Council.
Beijing said it had no advance warning of the test. Foreign Ministry spokeswoman Hua Chunying said China remained opposed to such tests and urged Pyongyang to take steps to prevent further deterioration of the situation. She also called for a resumption of the so-called six-party talks aimed at getting Pyongyang to abandon its nuclear program.
Those talks — involving the U.S., North Korea, China, Japan, South Korea and Russia — broke down in 2009 after six years, not long after Obama took office.
Whether Obama has the desire — or the bandwidth¿ — to make a bold move to get Pyongyang back to the negotiating table before his term runs out remains unclear.
Washington and Seoul have insisted that Pyongyang show sincerity by taking concrete steps toward denuclearization before resuming dialogue. But China, Russia and North Korea have called for an unconditional return to talks.
"Obama put in a tremendous effort to secure the Iran nuclear deal, which has been a successful and historic breakthrough. It shows that when the United States conducts deft, effective diplomacy to deal with a proliferation threat, it can work," said Kimball of the Arms Control Assn. "He has not taken the same political and diplomatic risk with North Korea during the course of his presidency."
At a joint news conference with South Korean President Park Geun-hye in Washington in October, Obama said he saw no sign that Pyongyang was serious about negotiating.
"At the point where Pyongyang says we are interested in seeing relief from sanctions and improved relations, and we are prepared to have a serious conversation about denuclearization, I think it's fair to say that we'll be right there at the table," he said.
In addition to testing Obama, Pyongyang's actions are a fresh challenge for the Chinese leadership, which is increasingly trying to assert itself as a major player in global affairs.
If confirmed, it would be the first nuclear test conducted by the North since Xi Jinping took office as China's president in March 2013. Although China is considered North Korea's only remaining major ally, and Xi is the most-traveled Chinese president in history, he has not visited North Korea, nor has he hosted a visit by the North Korean leader.
"China does have the ability to curtail trade and enforce the U.N. Security Council sanctions much better," Kimball said. "Their leverage is sometimes, I think, overstated, but still they do need to do more, and that can make an important difference on the margins."
Shi Yuanhua, director of the Center for China's Relations with Neighboring Countries at Fudan University in Shanghai, said it was up to Washington to shift its stance to get Pyongyang back to the bargaining table.
"Compared to the U.S., China is still an outsider in this matter," he said. "Technically, the U.S. and North Korea are still at war. They need a peace treaty and then to normalize diplomatic relations."
This week's test, Shi said, was a sign that North Korea wants to talk.
But there are few signs that either the Obama administration or Beijing are ready to shift gears.
China might be willing to step up diplomatic pressure on the North, said Bonnie S. Glaser, an expert on the country's foreign policy at the Center for Strategic and International Studies. But in the absence of a larger package on the table, she said, it would be loath to embrace tougher sanctions and abandon its "bottom-up strategy" of promoting economic engagement with North Korea, because that could create instability on its border.
"A lot of people think China is the missing link, and if only it would get on board with sanctions, that North Korea could be compelled to give up its nuclear weapons. The Chinese just don't look at it like that," she said.
For now, it appears North Korea will at least come in for a new round of knuckle-rapping.
Park, chairing an emergency meeting of South Korea's national security council on Wednesday, called the reported test "a grave provocation to our national security." South Korea also said it would "take all necessary measures … so that the North will pay the price for the nuclear test."
In Japan, Nihon Television reported that officials close to Prime Minister Shinzo Abe were discussing strengthening sanctions. Abe told reporters that Japan would join forces with the U.S. and China to take "firm countermeasures," according to Japan's public broadcaster NHK.
Russia also condemned Pyongyang's announced test as a "violation of international law." But Leonid Petrov, an expert on North Korea at the Australian National University, said any push for a resumption of six-party talks could be undercut by continuing tensions between Washington and Moscow.
"I'm sure China is going to be very angry about this, but Russia's response will probably be more balanced and less adverse," he said.
Russian experts have expressed doubt that North Korea has the technology to produce a hydrogen bomb, Petrov added.
"If it is confirmed they do have a thermonuclear weapon, Obama should spend the rest of his term negotiating with North Korea rather than abstaining," he said.
Rep. Mac Thornberry (R-Texas), the chairman of the U.S. House Armed Services Committee, said the U.S. cannot afford to focus only on Islamic State, Iran or Russia.
"We must be prepared to protect our national security against many threats," he said. "Unfortunately, the view around the world is that U.S. leadership is in decline while the administration's inaction only fuels those concerns."
Makinen reported from Beijing, Zavis from Los Angeles and Parsons from Washington. Yingzhi Yang in The Times' Beijing bureau, special correspondent Jake Adelstein in Tokyo and Times staff writer W.J. Hennigan in Washington contributed to this report.