North Korea conducted its third test of a nuclear device Tuesday, raising fears of instability in Northeast Asia and new questions about whether the isolated authoritarian regime can be stopped in its decades-long effort to develop nuclear weapons. The explosion was first suspected after a magnitude 5.1 earthquake was detected shortly before noon local time about 235 miles (380 km) northeast of the capital, Pyongyang, near the site of the country’s previous nuclear tests. The Japanese Prime Minister’s office held an emergency session, saying, “There is a possibility that a nuclear test was conducted by North Korea based on the previous cases.” About two hours later, North Korea’s state-run news service confirmed the test, which it said was conducted with a smaller and lighter device than previous detonations, “yet with great explosive power.”
The test follows North Korea’s successful December satellite launch, which demonstrated improved long-range missile technology. Last month North Korea’s National Defense Commission warned it would carry out a “higher level” nuclear test, which was targeted at the U.S. It comes two weeks ahead of the swearing-in of South Korean President Park Geun-hye, a sign of the sharp security tests that her new administration will face. It also coincides with heightened regional animosity in East Asia, with China and Japan at odds over East China Sea islets claimed by both nations. But North Korea’s test is a reminder that it remains the greatest regional security threat, with its leadership unbowed by international condemnation and its weapons capability apparently growing. The White House condemned the test as a “highly provocative act that, following its Dec. 12 ballistic-missile launch, undermines regional stability.”
North Korea previously tested nuclear devices in 2006 and 2009, which resulted in widespread international condemnation and heightened sanctions. But efforts to slow North Korea’s pursuit of deadly nuclear capability have had limited effect. A South Korean Defense Ministry official said North Korea is believed to have detonated a nuclear device with a strength of six to seven kilotons, Yonhap News Agency reported. That would be near the high end of the 2009 test, though more precise analyses will take time. Likewise, experts are waiting to see whether there is any indication that this device used plutonium fuel, as North Korea has said was used in its previous tests, or highly enriched uranium, which would indicate new capabilities that give it a huge supply of fissile material and make controlling its nuclear program even harder.
Like the missile launch in December, Tuesday’s test will invariably result in a new round of U.N. Security Council sanctions. But there is no guarantee they will have any more impact than past efforts at thwarting the country’s nuclear ambitions. “Any test, whether plutonium or uranium, will probably lead to additional international sanctions,” says Andrei Lankov, a North Korea expert at Seoul’s Kookmin University. “However, I’m very skeptical about the efficacy of sanctions. I don’t think they’re going to work. They’ve been under sanctions since 2006, and during this time the North Korea government has twice and now three times tested nuclear devices, missile launches and finally a successful satellite launch.”
The U.N. Security Council was scheduled to hold an emergency meeting early Tuesday. The response of China, a permanent member of the council and North Korea’s only significant ally, will be a key indication of whether new condemnation of the regime will have any significant consequences. China has traditionally been unwilling to endorse any moves that might destabilize its neighbor, particularly in the year since longtime leader Kim Jong Il died in December 2011 and power was transferred to his young and untested son Kim Jong Un. But last month China joined the rest of the Security Council in voting to tighten a number of existing U.N. sanctions, including barring some North Korean space-program and banking officials from foreign travel.
The Global Times, a nationalist Beijing-based newspaper, wrote last week that China should cut aid to North Korea if it goes ahead with a third nuclear test. “China has many misgivings when handling relations with Pyongyang, but there is a general principle: China is never afraid of Pyongyang,” the newspaper said in an editorial. “Pyongyang’s diplomacy is characterized with toughness. But if Pyongyang gets tough with China, China should strike back hard, even at the cost of deteriorating bilateral relations.” While the Global Times is run by China’s ruling Communist Party, its editorials aren’t considered official policy thinking and can often reflect a more strident line.
The test coincided with the Chinese New Year holiday, when most of China is on vacation. The Chinese Foreign Ministry issued a brief statement saying it “resolutely” condemned North Korea’s act and urged it to “no longer carry out actions that could worsen the situation.” The test will put pressure on the new administration of incoming leader Xi Jinping to rein in the Kim regime. And there were signals that the Chinese public’s patience with North Korea was wearing thin. “If someone who claims to be an ‘intimate neighbor’ and good friend sets off a nuclear device at your doorstep, would you still treat him as a friend?” Zhang Xingsheng, northeast Asia director of the Nature Conservancy, wrote on his Sina Weibo microblog. “What should China do with such a neighbor? Permit it to continue being reckless?” While many Chinese writing online agreed with the sentiment, China might only go so far to constrain its neighbor. “My view is that Beijing recognizes the growing threat from the North Korean issue to comprehensive regional security,” Zhu Feng, an international-studies professor at Peking University, told TIME. “It will force Beijing to move forward, but the problem is, to what extent? At least I see Beijing growing in willingness to build coordination with the U.S., Japan, South Korea and Russia.”
— With reporting by Yue Wang / Hong Kong