North Korea conducted an underground nuclear test on Tuesday, prompting President Barack Obama to call the detonation of a miniature nuclear device a “highly provocative act” that threatens U.S. security and international peace. It is the third nuclear test by Pyongyang since 2006 and is escalating concern that the isolated Stalinist state is now closer to building a bomb small enough to be fitted on a missile capable of striking the United States and its allies. The test was conducted hours before Obama’s annual State of the Union speech.

North Korea’s official Korean Central News Agency said the test was conducted, “in a safe and perfect way … with the use of a smaller and light A-bomb, unlike the previous ones, yet with great explosive power.” The statement said the nuclear device did not impose “any negative impact” on the environment.

North Korea said the atomic test was merely its “first response” to what it called U.S. threats and said there would be unspecified “second and third measures of greater intensity” if the United States remains hostile to the North. Washington had led the call for more U.N. sanctions against Pyongyang after the North launched its first rocket and put a satellite into obit in December. While the North said the launch was for its civilian space program, the Obama administration believes it was part of a covert program to develop ballistic missiles that can carry nuclear warheads.

We ask two Stanford experts on North Korea to weigh in: David Straub, the associate director of the Korean Studies Program at the Walter H. Shorenstein Asia-Pacific Research Center (APARC), and Nick Hansen, an affiliate of the Center for International Security and Cooperation who is an expert in foreign weapons systems.   

Q. Why conduct the test now?

Straub: Since the two previous North Korean nuclear tests took place on American holidays and the North Korean themselves have announced that their moves are "targeted" at the United States, many observers have concluded that the this test was especially timed to coincide with President Obama's State of the Union address. It is also possible that, as others have speculated, the North Koreans also took into account that Feb. 16 is the birthday of North Korean leader Kim Jong Un's father, Kim Jong Il, the man who is said to have instructed North Koreans to proceed with the nuclear weapons and missile programs. Others have speculated that the North Korean leadership wanted to test the device before the Feb. 25 transition in South Korea from the current president Lee Myung-bak, to the president-elect, Park Geun-hye. The timing could be intended to punish Lee, whom the North Koreans say they despise, while, the argument goes, making it a little easier for Park to reach out to the North before her inauguration.

Q. What message is North Korea’s young and relatively new president, Kim Jong Un, trying to send to the world with this test?

Hansen: Kim seems to be saying: I’m going to do what I say I’m going to do – and nobody is going to dissuade me. The North said they were going to launch a satellite, and by God they did. They said they were going to touch off a nuclear test after that, and by God they did. Now we have to wait and see what’s next.

Straub:  The North Koreans themselves are saying that the test is a response to the military threat posed to it by the United States and to U.S.-led UN sanctions imposed on North Korea after its rocket test in December. The North Koreans have complex motivations for pursuing nuclear weapons. Many North Koreans may actually believe that having nuclear weapons will defend them against the United States. But the fact of the matter is that the United States and South Korea have never attacked North Korea over the decades, while the North Koreans have repeatedly attacked South Korean and American targets, most recently killing 50 South Koreans in 2010. North Korea's top leaders see nuclear weapons and missiles as a panacea. Fearful of opening up to the outside world because of the lies they have told their people, Pyongyang wants to believe that it will eventually maneuver the United States and the international community as a whole into accepting its possession of nuclear weapons and forcing the removal of sanctions against it. That won't happen, but even if it did, it would not resolve Pyongyang's basic problems, which stem from the totalitarian nature and history of its regime.

Q. What concerns you most in the wake of this test?

Hansen:  The thing I’m worried about now is that they also said they’re going to launch more satellites and long-range missiles. They displayed one in the military parade of 2010, an intermediate-range missile that can probably go 2,000 miles. When you think about that, 2,000 miles, or maybe a little bit longer, it puts just about every U.S. base in Asia under its threat, including Guam, Okinawa, Taiwan and everything in Japan. It’s a threat if they could put a warhead on it. The KN-08 is a bigger, three-stage rocket and is more of a threat, with the potential of hitting at least Alaska, Hawaii and maybe the U.S. West Coast. But remember, the North has tested neither.

Q. The test was in defiance of Pyongyang’s chief ally, Beijing, which had urged Kim not to risk confrontation and said the North would “pay a heavy price” if it proceeded with a test. How will China respond?

Straub: China is key in dealing with the North. China provides North Korea with most of its external support, including vital food and energy supplies. Chinese leaders are certainly not happy with their North Korean counterparts, as China would prefer peace and stability in the region, so it can focus on its own economic development. But Chinese leaders are fearful that putting a great deal of pressure on North Korea might result in chaos, with unpredictable and possibly very dangerous repercussions for China and the region. Thus, before North Korean nuclear and rocket tests, typically the Chinese press Pyongyang not to proceed. But immediately after a test, the Chinese begin to urge "all parties" to exercise restraint. In the United Nations, where China has a veto on the Security Council, it reluctantly agrees to the minimum condemnations of and sanctions against North Korea. After the dust settles, however, China doesn't seriously implement the sanctions. In fact, since North Korea conducted its first nuclear test in 2006, Chinese trade with North Korea has dramatically increased as a result of a PRC government decision to support North Korea. China may agree to a stronger resolution this time, but ultimately this pattern will almost certainly repeat itself.

Q. The North Koreans have said the test poses no risks to the environment or its people. Is this accurate?

Hansen: It takes a while for the particles that are released from the test to get released from the cracks in the rock and get into the atmosphere. My guess is that because of this very hard rock, they probably don’t have much of a radiation release problem. It probably will just seep through naturally and should not be of any danger. Engineers seem to have done a good job from a security and safety standpoint; the way the tunnels make right-handle turns and then there are the blast doors and piles of dirt to soak up any release.

North Korea Timeline

North Korea successfully launched a long-range rocket Wednesday, with the North American Aerospace Defense Command (NORAD) confirming Pyongyang had "deployed an object that appeared to achieve orbit." The defiant rocket launch has prompted worldwide consternation: Japan has called for an urgent meeting of the U.N. Security Council; the Obama administration called the launch a "highly provocative act that threatens regional security" and violates U.N. resolutions; and South Korea has raised its security threat level. 

Pyongyang insists it has a right to pursue a peaceful space program and that the rocket was armed with a communications satellite to help in that endeavor. But the U.S. and its allies worry the technology could lead to an intercontinental ballistic missile capable of carrying a nuclear warhead.  

We turn to three experts on North Korea for their views on the launch: David Straub, associate director of the Korean Studies Program at the Walter H. Shorenstein Asia-Pacific Research Center; Thomas Fingar, an international intelligence expert and the Oksenberg-Rohlen distinguished fellow at FSI; and Nick Hansen, a CISAC affiliate and expert in foreign weapons and imagery intelligence who writes for Jane’s Defense and 38North.org, a website for the U.S.-Korea Institute at SAIS.

Why is the global community surprised North Korea has successfully launched a rocket and apparently put a satellite into orbit? 

Straub: It shouldn't come as a surprise that North Korea has finally succeeded with its fifth test of a long-range rocket, which it's been trying to do since 1998. North Korea has pursued the development of nuclear weapons and missiles with great determination and intensity over many decades, because its leaders regard these as a panacea for problems actually originating in their own failed economic and political systems. 

Fearful that domestic reform would result in their overthrow, they continue to oppress and isolate their people while using military threats to intimidate other countries. Their aim is to remain in power and eventually prevail over their rival South Korea by forcing the lifting of international sanctions and being accepted as a nuclear weapons state. It is not irrational but it is very unrealistic. Most members of the international community, including the United States, will never accept this. North Korea is thus going ever deeper down a blind alley. 

The rocket technology is dangerously close to long-range missile technology and the United Nations Security Council has issued several resolutions and forbidden North Korea from conducting any further tests. 

Was there any significance to the Dec. 10-29 launch window? 

Straub: The media is full of speculation about why North Korea announced this particular window of dates, such as that it means to send a message to the Obama administration or to influence the upcoming South Korean presidential election on December 19.  My own guess is that it is keyed to the first anniversary Kim Jong Il’s death on December 17. 

But in the end, the most important question is why the North Koreans conducted the launch. It is fundamentally because they have a long-standing missile program to which they have devoted a great deal of resources. If the leadership had devoted those resources to taking care of its citizens, it could have bought enough food on the global market to prevent hunger, instead of calling on the international community for assistance.

The North Koreans typically pick the spring or summer to test their rockets. Why did it launch now amid constraining winter weather? 

Hansen: The timing is purely political. The reasons they prefer to launch in the spring and summer are, of course, better weather conditions and longer days to work on the pad. But the anniversary of the death of Kim Jong Il, the presidential elections in South Korea, beating the south to a satellite launch or putting the DPRK back in the international spotlight – these could all have driven the decision. 

North Korea may be following the same script they used for the (failed) April 12 Unha-3 launch. If they continued at the April pace, the rocket should have been completely stacked on the pad on Dec. 7 in order to be checked out on the 8^th and 9^th and be ready to launch on the 10^th, which was the first day of the launch window. This was a tight schedule with little room for technical problems or weather delays. (The North's Korean Central News Agency announced Dec. 10 that the launch window had been extended to the 29th, thus catching many North Korea observers off guard by the earlier launch.) 

Fingar: The timing is indeed outside the normal window of relatively better weather. Possible factors include commemoration of the anniversary of Kim Jong Il’s death; a ploy to capture the attention of new administrations in Washington, Beijing, Seoul, and Japan; and intent to buttress the North’s claim to having a nuclear deterrent by demonstrating that it can launch at any time of the year. There might also have been a simpler explanation, namely that DPRK engineers thought they had found and fixed the problem that caused the previous tests to fail and persuaded Kim Jong Un that there was no technical reason to delay.

What are the larger implications of North Korea’s actions and why do these rocket launches provoke such global condemnation? 

Fingar:  Perhaps the primary reason is that North Korea is widely perceived to be dangerous and more than a little bizarre. In other words, it is an easy target and symbolic embodiment of “worst case” fears about what a defiant and “irrational” country might do with its nuclear and missile capabilities. 

The world also sees that North Korea’s attempt to launch a satellite is interpreted, not unreasonably, as defiance of U.N. Security Council Resolution 1718, which demands that the DPRK not conduct any further nuclear test or launch a ballistic missile. Pyongyang argues that a rocket used for space launches is not a ballistic missile, and therefore is not proscribed by the U.N. resolution. 

Straub: North Korea has been developing medium- and long-range missiles for more than two decades, during which time it has repeatedly attacked South Korea and threatened the United States and other countries. It has also been working on its nuclear program and has already tested two nuclear devices. The fear is that North Korea is trying to miniaturize a nuclear device that could be used as a warhead on a long-range missile. 

In January 2011, former Defense Secretary Robert Gates voiced U.S. concern that North Korea was becoming a direct threat to it, and that Pyongyang could successfully develop intercontinental ballistic missile capability within five years.  

In South Korea, the launch is unlikely to have a major impact on the presidential election December 19. Conservative South Koreans regard North Korean behavior as stemming from the nature of its system, while progressives also blame the policies of the United States and conservative South Korean administrations for making North Korea feel insecure. Each side will simply interpret the launch from its longstanding perspective on North Korea.  

In Japan, where concern about North Korea runs deep both because of the nuclear and missile programs and North Korea's abduction of Japanese citizens, the launch will likely further strengthen the front-running conservatives in the Lower House election on December 16.

How is the international community responding to the launch? 

Straub: The United States has already signaled that it will seek even stronger international sanctions against North Korea. If China is unwilling to agree in the U.N. Security Council, the United States and its allies will pursue increased sanctions on their own. 

China has again been embarrassed by North Korea, but there is no indication that it will change its basic policy of supporting North Korea for fear it might collapse, creating an unpredictable situation on China's border. Even if China agrees to some increased sanctions against North Korea in the UN Security Council, its record of actually enforcing international sanctions is decidedly mixed. In any event, it has dramatically increased its economic support for and engagement with North Korea since that country's first test of a nuclear device in 20006. 

Is there anything more that Washington can do to prevent these provocations by the North aside from pushing the Six Party Talks and threats of greater sanctions? 

Fingar:  Probably not. Some argue that Pyongyang’s goal is to use the provocations to persuade the United States to negotiate directly with North Korea, but its conditions for doing so include U.S. acknowledgment – and acceptance – of the North’s self-proclaimed status as a nuclear weapon state. That is not likely to happen. I think the best course for the United States would be to avoid over-reacting and to focus attention on Pyongyang’s defiance of U.N. Security Council resolutions.

There is speculation that a third underground nuclear test will follow the rocket launch if it fails to put a satellite into orbit.

Hansen: I believe they will test regardless of the successful launch.  I have been following the nuclear test site at Punggye-ri all November. Details from a Nov. 19 image show that part of the dirt road into the complex from the valley is unusable, as three bridges have been washed out. Instead they have upgraded an old road that runs up the west side of the valley and enters the complex just in front of the new south tunnel. Imagery on Nov. 24 revealed some changes. The new road is still being used and there appears to be more vehicle tracks going to the support area. The most significant development is the probable clearing of snow at the entrance to the south tunnel. It also appears that the mine cart tracks are being reinstalled on the spoil pile to carry dirt out from the tunnel, but I can't be sure of that. 

See our interactive timeline on key events in North Korea here at Storify.com 

Hansen Interview with the Australia Broadcasting Corp. 

Hansen's Q&A with Popular Science with Popular Science on Why Launch Doesn't Spell Doom 

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