North Korea claimed it successfully tested a hydrogen bomb on Jan. 6, according to a broadcast from the nation’s Korean Central Television. Experts at the Freeman Spogli Institute for International Studies offered their analyses to media.

Scholars from the Walter H. Shorenstein Asia-Pacific Center (APARC) and the Center for International Security and Cooperation (CISAC) contributed to a Stanford news release. Although the scholars said they are skeptical of North Korea’s claim, they also said the test would have a destabilizing effect on the region.

In a Q&A, Siegfried Hecker answered nine questions, offering perspective on the situation and how the United States should respond. Hecker, a CISAC senior fellow, is a former director of the Los Alamos National Laboratory and has visited North Korea seven times since 2004.

David Straub, associate director of the Korea Program, commented on the North Korean nuclear program in an NK News article. He said the timing of the nuclear test, now the nation’s fourth, was likely only marginally influenced by external factors such as Kim Jong-un’s birthday. The primary factor is technical, he said. Straub also spoke with Yonhap News on Feb. 12. In the interview, Straub said "although the United States and the People's Republic of China certainly have differences [in dealing with the North Korean nuclear issue], they pale in comparison to U.S.-Soviet differences." 

Straub also offered, in an extended interview with South Korea's Segye Ilbo newspaper, his thoughts on Pyongyang's motivations for pursuing nuclear weapons. He argued that the appropriate policy response is to continue to increase pressure on the regime. Pressure applied by Washington is meant to convince Pyongyang that nuclear weapons will bring more cost than benefit, while holding open the door to good-faith negotiations to resolve peninsular issues.

Shorenstein APARC Associate Director for Research Daniel Sneider talked with Al Jazeera America and Slate about the developments. He said the nuclear test signified North Korea’s uneasiness and was largely an accommodation of domestic politics.

In early February, South Korea announced temporary closure of Kaesong Industrial Complex (KIC), a jointly held project with North Korea. In Chosun Ilbo newspaper, Straub argued that South Korea's closure of KIC was a necessary response to North Korea's fourth nuclear test and latest satellite rocket launch. Two articles were published in Korean; the first is available here and the second here.

Stanford nuclear experts said they were skeptical of North Korea’s claim that it had detonated a hydrogen bomb this week.

However, they said the test was an important step forward for North Korea’s nuclear program and would have a destabilizing effect on the entire region.

“I don’t believe it was a real hydrogen bomb, but my greatest concern is not so much whether or not they actually tested a hydrogen bomb, but rather that they tested at all,” said Siegfried Hecker, former director of Los Alamos National Laboratory and senior fellow at Stanford’s Center for International Security and Cooperation.

North Korean dictator Kim Jong-un has “a track record of exaggerated statements, hyperbole and outright lies,” according to Scott Sagan, Caroline S.G. Munro professor of Political Science.

“The propaganda machine in North Korea has made all sorts of claims about Kim Jong-un’s personal prowess and his history, and it is totally unsurprising that he might make exaggerated claims about North Korea’s military prowess,” Sagan said.

Former U.S. Secretary of Defense William J. Perry said he also doubted that North Korea had detonated a two-stage hydrogen bomb.

“Whether it’s a hydrogen bomb or not, it’s very dangerous, destabilizing development,” said Perry.

“It’s obvious they’re working to increase the capability and size of their nuclear arsenal and that represents a huge danger to the region and creates major instability and major concerns on the part of South Korea and Japan.”

Many North Korea watchers had been anticipating another nuclear test.

“We’ve thought that the North Koreans could test at any time – that the tunnels were ready, that they could do this at any time – so it would be a political decision, not a technical decision,” said Thomas Fingar, senior fellow at the Freeman Spogli Institute for International Studies.

Hecker said North Korea’s latest nuclear test would move the country closer to being able to miniaturize a nuclear warhead and mount it on a missile, extending the reach of their nuclear weapons.

“They will have achieved greater sophistication in their bomb design – that is the most worrisome aspect,” Hecker said.

“At this point, what makes their nuclear arsenal more dangerous is not so much explosive power of the bomb, but its size, weight and the ability to deliver it with missiles.”

On the diplomatic agenda, the U.S. and its allies will likely push for stronger sanctions in the wake of the tests, according to Kathleen Stephens, a former U.S. Ambassador to the Republic of Korea and William J. Perry fellow at Walter H. Shorenstein Asia-Pacific Research Center (APARC).

“In the UN the U.S., Japan and South Korea will likely look for another, and stronger, UN Security Council resolution, presumably with some efforts to attach to it some teeth and strengthen sanctions,” Stephens said.

The U.S. Congress is currently considering financial sanctions that would cut of all access to U.S. banks for any banks dealing with the North Koreans.

But financial sanctions would likely be less effective in dealing with North Korea than they had been with Iran, according to Fingar.

“It’s like hitting a masochist,” said Fingar.

“North Korea is relatively insulated from the external economy, where Iran wasn’t. Iran had a middle class, you could make sanctions hurt, they could have a real effect. You could make it hard for the North Koreans to buy luxury goods, but at the end of the day, is that going to bring down the regime?”

Financial sanctions against North Korea could have the unintended consequence of also hurting China, said David Straub, associate director of the Korea program at APARC.

“This could be problematic for China because many of the transactions that North Korea conducts would be going thorough Chinese banks, and the Chinese, understandably might not be happy about the US financial sanctions on them, in effect,” Straub said.

Perry recommended that the U.S. reinvigorate diplomatic talks with North Korea in collaboration with China, South Korea, Japan and Russia.

“I would not give up on negotiations with North Korea yet,” Perry said.

“What could have been done many years ago was following through on negotiations with North Korea at the turn of the Century, which were proceeding robustly in the last years of Clinton’s second term, but were abandoned by the Bush Administration...That was a geo-strategic error.”

But Hecker said those negotiations would be harder now.

“I have previously argued that we should focus on three “No’s” for three “Yes’s” – that is no more bombs, no better bombs (meaning no testing) and no export – in return for addressing the North’s security concerns, its energy shortage and its economic woes,” said Hecker.

“This could have worked when I first proposed it 2008 after one of my seven visits to North Korea. It will be more difficult now."

Former Los Alamos National Laboratory director Siegfried Hecker assesses North Korea’s claim to have detonated a hydrogen bomb in an underground nuclear test this week. Hecker is one of the world’s top experts on the North Korean nuclear program. He has visited North Korea seven times since 2004, and is the only Western scientist known to have ever been inside a North Korean uranium enrichment facility. He is currently a senior fellow at Stanford’s Center for International Security and Cooperation, and a research professor of Management Science and Engineering.

Do you believe that North Korea actually detonated a hydrogen bomb in its latest nuclear test?

I don’t believe it was a real hydrogen bomb, but my greatest concern is not so much whether or not they actually tested a hydrogen bomb, but rather that they tested at all. Since this test worked, they will have achieved greater sophistication in their bomb design – that is the most worrisome aspect. This is their fourth test – with each test they can learn a lot.

What makes a hydrogen bomb a more threatening weapon than a conventional atomic bomb?

A hydrogen bomb can be a hundred or a thousand-fold more powerful than a fission bomb. Certainly a blast of a megaton will be much more destructive than the Hiroshima bomb, but the more important part is the ability to deliver at long range and to do it accurately. That is what would threaten the United States and its allies most; even with the size of nuclear blasts they have already demonstrated.

White House officials say that initial data from nearby monitoring stations are not consistent with a hydrogen bomb test. How will we know for sure whether it was a hydrogen bomb or not?

The short answer is that we may never know. The telltale signs of a hydrogen bomb are very difficult to pick up in a deeply buried test. Typically hydrogen bombs have greater explosive power or yield. This test is currently believed to have resulted in a seismic tremor of 5.1 on the Richter earthquake scale. That would make it roughly equivalent to the third nuclear test in February 2013. At that time, North Korea claimed it tested a miniaturized atomic bomb – there was no mention of a hydrogen bomb. My estimate of the yield for the 2013 test is roughly 7 to 16 kilotons – which is in the range of the 13-kiloton Hiroshima blast. As far as destructiveness, a Hiroshima-scale explosion is bad enough. Detonated in Manhattan, it may kill as many as a quarter million people. The power of the 2013 and the current explosion is more consistent with fission bombs than hydrogen bombs.

Can you rule out the possibility that it was a hydrogen bomb?

I find it highly unlikely that the North tested a real hydrogen fusion bomb, but we know so little about North Korea’s nuclear weapons design and test results that we cannot completely rule it out. A modern hydrogen bomb is a two-stage device that uses a fission bomb to drive the second stage fusion device. A two-stage device is very difficult to design and construct, and is likely still beyond the reach of North Korea today. However, by comparison, China’s early nuclear weapon program progressed rapidly. It tested its first fission bomb in 1964 and less than three years later demonstrated a hydrogen bomb – and that was 50 years ago. North Korea has now been in the nuclear testing business for almost 10 years, so we can’t rule anything out for certain.

If it wasn’t a hydrogen bomb, what kind of bomb might it have been?

What may be more likely than a two-stage hydrogen bomb is that they took an intermediate step that utilizes hydrogen (actually hydrogen isotopes) fuel to boost the explosive yield of the fission bomb, a sort of turbocharging. Such a device has a fusion or “hydrogen” component, but is not a real hydrogen bomb. It allows miniaturization – that is making the bomb smaller and lighter. Moreover, it would be the first step toward eventually mastering a two-stage hydrogen bomb.

The most important aspect then is to miniaturize, whether it is a fission bomb, a boosted fission bomb, or a hydrogen bomb. The Nagasaki bomb weighed 5,000 kilograms. It was delivered in a specially equipped B-29 bomber. North Korea wants to demonstrate it has a deterrent. To do so, it needs to be able to credibly threaten the U.S. mainland or our overseas assets. For that, you have to make the bomb (more correctly, the warhead) small enough to mount on a missile. The smaller and lighter, the greater the reach. At this point, what makes their nuclear arsenal more dangerous is not so much explosive power of the bomb, but its size, weight and the ability to deliver it with missiles.

How close is North Korea to being able to credibly threaten a nuclear strike against the mainland United States?

North Korea is still a long way off from being able to strike the US mainland. It has only had one successful space launch. It needs a lot more, but it has a large effort in that direction.

Do you think North Korea conducted this test for political or technical reasons?

North Korea had very strong technical and military drivers for this test, as well as follow-on tests. The political environment is mostly what has constrained it from testing earlier and more often. However, this test demonstrates that Pyongyang is willing to weather the political storm this test will bring. It has done so for all previous tests.

What are your current estimates on the size of North Korea's stockpile of nuclear weapons and materials?

Much like in the area of sophistication of the bomb, we have little information of what North Korea actually possesses. The best we can do is to estimate how much bomb fuel, plutonium and highly enriched uranium, they may have produced and estimate how many bombs they can produce from that stockpile. My best estimate at this time is that they may have enough bomb fuel for 18 bombs with a capacity to make 6 to 7 more annually. That, combined with the increased sophistication they surely achieved with this test, paints a troublesome picture.

How should the U.S. respond?

I am concerned about we haven’t done to date. Washington has lost many opportunities we have had since North Korea began its nuclear weapon production in earnest in 2003. One thing that’s clear is that doing what we and the rest of the world have done so far – half-hearted diplomacy, ultimatums, and sanctions – have failed, so these are not the answer. I have previously argued that we should focus on three “No’s” for three “Yes’s” – that is no more bombs, no better bombs (meaning no testing) and no export – in return for addressing the North’s security concerns, its energy shortage and its economic woes. This could have worked when I first proposed it 2008 after one of my seven visits to North Korea. It will be more difficult now.

In an NK News' series of interviews with a panel of U.S. experts on North Korea policy, David Straub, associate director of the Korea Program and former State Department Korea director, analyzes the U.S. approach toward Pyongyang. With NK News' permission, downloadable PDF versions of the interviews are available below.

Weeks away from a final international accord on Iran’s nuclear program, Stanford scholars are focusing on the technical, political and practical aspects of the pending deal intended to loosen sanctions while restricting Tehran’s ability to build a nuclear weapon.

“In two to three weeks we will have what some pundits are already calling the most revolutionary positive change in Iranian-American relations and others are saying a disastrous policy of appeasement to the Iranian regime,” said Scott Sagan, a senior fellow at the university’s Freeman Spogli Institute for International Studies. Sagan moderated a discussion at the FSI's Center for International Security and Cooperation (CISAC) on Tuesday that included FSI’s Siegfried Hecker and Thomas Fingar, as well as Abbas Milani, director of Stanford’s Iranian Studies.

Hecker, a former director of the Los Alamos National Laboratory, said Iran has developed its civilian nuclear capabilities to concurrently have a nuclear weapon option. However, at this point, they do not yet have nuclear weapons, nor have they produced the fissile materials, plutonium or highly enriched uranium, that would fuel such weapons.

“They’ve demonstrated they can enrich uranium to the levels allowed for civilian applications, but that gives them the capability to produce highly enriched uranium for bombs should they choose to do so,” Hecker said. “If they complete the Arak reactor, they will have the potential for plutonium production, although they have not developed a facility to extract the plutonium. If you look in terms of timelines for making fissile materials, they were somewhere between weeks to a month or two away for making enough fissile material for one bomb at the start of the negotiations in November 2013. The nuclear deal would move that timeline, called the ‘breakout’ time to one year, giving the international community more time to respond.”

Hecker said the technical issues are “secondary to whether Iran actually wants to go ahead and decide to build the bomb.”

He met with Iranian negotiators – including Foreign Minister Mohammad Javad Zarif – in 2013, and said the officials were anxious to reach a deal.

“Zarif told me that the cost of acquiring strategic capabilities will make Iran less safe rather than more safe,” Hecker said.

Fingar, who chaired the National Intelligence Council while also serving as the U.S. deputy director of national intelligence for analysis between 2005 and 2008, stressed the need for strong verification mechanisms if any deal with Iran is going to work.

“Verification can establish some facts but what it means is fundamentally a contextual and political judgment. What is most important? Catching somebody in a technical violation or preserving the overall purpose for which you are conducting verification. Verification requirements are an integral part of the negotiating process,” Fingar said.

That is especially true for Iran, which has proven that it is not trustworthy, he said.

“It did have a military program, it was seeking the bomb. It continues to lie about it. It lied to the European negotiators, to the UN, to the IAEA,” Fingar said. "This history mandates having a rigorous verification capability."

Monitoring is done in three bins, he said. The first, and most important, is the IAEA on-site inspections. The second is that done by other countries’ intelligence services, including those of the other P5 plus 1 countries and Israel. The third bin is the U.S. intelligence community.

“We will learn far more about what Iran is doing from the IAEA inspections than from any other mechanism,” Fingar said.

Milani focused on the politics of the deal inside Iran. Discussion of this political dimension, he said, cannot be understood unless we take into account two critical issues: Recent concerns with the health of Iran’s supreme leader, Ayatollah Ali Khamenei, and the heated battle on who might succeed him; and secondly the rise of ISIS and the fact that they are near Iran’s borders and have repeatedly threatened the country’s Shiites.

The debate in Iran is heated, he said, with many in favor of the agreement and a few opposed to it.

“Part of what is being fought over is what happens after the deal,” he said. “Who can claim victory for the deal? Who can take blame for it? These are profoundly political issues and they are being fought over.”

Milani said that he has never seen any policy issue, in the entire 35-year history of the Islamic Republic, being discussed with as much detail, and with as much ferocity as the nuclear deal.

There are occasional, detailed debates happening in Tehran University and other places Milani said. One side –typically pro-regime hard-liner – argues that this is the worst deal in Iran’s history. Reformists and scholars supporting President Rouhani’s government defend the agreement.

But he said these conservative opponents of the agreement are in the minority. He estimates that they have no more than 7 to 10 million supporters in a country with a population of 75 million. The vast majority of the population wants a deal, he said. The Iranian Revolutionary Guard Corps, which wields more power than any other group, is not all in favor of the deal and has made threats against the government in recent weeks.

Still, the ultimate political obstacle is that the deal must contain language that all actors can sell to their respective constituencies as a victory. And finding a language that passes this political hurdle is every bit as hard as the problems discussed by Hecker and Fingar.

Joshua Alvarez is a freelance writer.

The threats, turmoil, and media circus surrounding the Hollywood satire "The Interview," in which bungling American journalists assassinate North Korean leader Kim Jong Un, have put the country in the international spotlight again. Often forgotten amid all this comedy, though, is the very unfunny fact that North Korea’s nuclear weapons program has been relentlessly expanding for a decade, and poses a real and deadly threat to the rest of Northeast Asia.

Senior Fellow Siegfried Hecker writes in this Bulletin of the Atomic Scientists piece that North Korea today may possess a nuclear arsenal of roughly 12 nuclear weapons, half likely fueled by plutonium and half by highly enriched uranium.