North Korea tests a nuclear device, South says

PHOTOGRAPHER: The New York Times

SEOUL, South Korea — North Korea conducted its fifth underground nuclear test on Friday, South Korean officials said, despite threats of more sanctions from the United States and the United Nations. The latest test, according to the officials, produced a more powerful explosive yield than the North’s previous detonations, indicating that the country was making progress in its efforts to build a functional nuclear warhead.

A statement from the South Korean military also said that an artificial tremor, registered as magnitude 5.0, had originated from Punggye-ri in northeastern North Korea, where the North has conducted its four previous underground nuclear tests.

A senior Defense Ministry official later told reporters that his ministry had concluded that the tremor was caused by a nuclear detonation.

The ministry estimated the explosive yield as being equivalent to 10 kilotons of TNT, the most powerful detonation unleashed in a North Korean nuclear test so far, according to the official, who briefed reporters on condition of anonymity. The South Korean government estimated the North’s last nuclear test, conducted in January, at 4.8 magnitude with an explosive yield of 6 to 9 kilotons. (By comparison, the atomic bomb dropped on Hiroshima in 1945 exploded with 15 kilotons of energy.)

Prime Minister Hwang Kyo-ahn of South Korea called an emergency meeting of top security officials, while his boss, President Park Geun-hye, cut short a visit to Laos, the president’s office said.

The episode unfolded less than a day after President Barack Obama concluded the final Asian tour of his presidency and highlighted the conundrums that the North Korean threat presents to the United States and China, which have often been at odds over how to respond to the bellicose acts of North Korea’s leader, Kim Jong Un.

In Washington, Ned Price, a National Security Council spokesman, said: “We are aware of seismic activity on the Korean Peninsula in the vicinity of a known North Korean nuclear test site. We are monitoring and continuing to assess the situation in close coordination with our regional partners.”

The nuclear test sets the stage for a new round of tensions on the divided Korean Peninsula, and heightens anxieties elsewhere in Asia and beyond. For the past two decades, Washington has been struggling in vain to stop North Korea’s bellicose, anti-American leaders from arming the country with nuclear weapons.

Although it was long thought that North Korean nuclear and missile tests were intended as muscle flexing for both internal and external consumption, and as a way to exact concessions from the great powers,a growing number of experts and officials say that the North may be committed to assembling a nuclear arsenal that would include smaller weapons that could be mounted on short-range missiles.

Park said later on Friday that the latest test proved a “fanatical recklessness of the Kim Jong Un regime.”

“The only thing the Kim Jong Un regime will get from this nuclear test will be more intensified sanctions from the international community and deeper isolation,” Park said. “This kind of provocation will only quicken its eventual self-destruction.”

Prime Minister Shinzo Abe of Japan said if a test had been conducted, “it simply cannot be justified.” He added that he had instructed government security analysts to collect as much information as possible and share it with the United States, South Korea, China and Russia.

There was no immediate official reaction from China, North Korea’s biggest economic benefactor and closest political ally, though the state-run People’s Daily reported on its social media account that “tremors were strongly felt” in the Chinese city of Yanji on the border with North Korea.

Though Beijing’s relations have been strained over Pyongyang’s growing nuclear ambitions, China’s leader, Xi Jinping, has refrained from severely punishing Kim.

The Obama administration has pointed to North Korea as one of the issues where China and the United States could work together, and praised China for supporting U.N. sanctions imposed this year against North Korea.

But reports from the border region with North Korea show that Chinese trade continues, and Washington and Beijing increasingly differ on how to deal with the North’s nuclear program.

When South Korea agreed in July to the U.S. request to deploy an anti-missile system, known as the Terminal High Altitude Area Defense system, as protection against North Korea’s nuclear weapons, China strongly protested and even suggested that the deployment was as provocative as the North Korean tests.

At the meeting between Obama and Xi in Hangzhou, China, last week, the Chinese leader reiterated his opposition to the deployment of the Thaad system, asking the United States to respect China’s strategic interests.

One of China’s biggest fears is a collapse of North Korea that would result in a unified Korean Peninsula under an American defense treaty. For that reason, Chinese analysts say, China has tolerated Kim’s advances in nuclear weapons.

North Korea last tested a nuclear device on Jan. 6. In April, Park warned that the North might be preparing for another underground nuclear test in defiance of U.N. sanctions.

Friday will be the 68th anniversary of the founding of the North Korean government. The country often celebrates its major holidays with displays of military might. Last week, it fired three ballistic missiles into the sea between the North and Japan, prompting the U.N. Security Council to urge the North to stop provocations or face more sanctions.

In March, the North Korean state news media reported that Kim had ordered that a “nuclear warhead explosion test” be conducted soon, as well as tests of ballistic missiles capable of delivering nuclear warheads. North Korea has since launched a series of ballistic missiles, including one fired from a submarine last month.