(The following interview with CISAC's Siegfried Hecker appeared in the May 15 issue of the Bulletin of the Atomic Scientists.)

By Elisabeth Eaves

Siegfried Hecker has the rare distinction of being an American who has visited both North Korean and Russian nuclear facilities. An expert on plutonium science and a professor at Stanford University’s Center for International Security and Cooperation, Hecker is also a former director of the Los Alamos National Laboratory. Here he answers questions on Pyongyang’s nuclear capabilities, its most recent missile test, and what influence the new president of South Korea might have on the regional balance of power. He explains how North Korea developed its arsenal despite global opposition, and says there is no conceivable way the United States can destroy all North Korean nuclear weapons with military might.

BAS: Is North Korea currently capable of delivering any nuclear weapons any distance? How do you know?

SH: We know they have nuclear weapons that work because they have tested five nuclear devices over a period of 10 years. That test experience most likely enables them to miniaturize nuclear warheads to make them small and light enough to mount on missiles. They have also demonstrated over many years that they can launch relatively short-range missiles reliably. We have to assume they can mate the warheads and the missiles so as to reach targets anywhere in South Korea and Japan.

BAS: What does Pyongyang’s most recent missile test, which took place on Sunday, tell us about their capabilities and intentions?

SH: The missile experts are still analyzing the test as North Korea releases details and photos. However, they already agree that this missile outperformed any previous North Korean missile launch. It is reported to have traveled nearly 800 kilometers (497 miles) for 30 minutes (splashing down in the Sea of Japan south of the Russian border) and reached an altitude in excess of 2000 km (1243 miles). Since it was launched in a lofted trajectory, it may be able to travel at least 4,000 km (2486 miles) if launched on a standard trajectory. 

This would make it a real intermediate-range ballistic missile that puts Guam within range. But the more important objective of this test was to move North Korea closer to having an intercontinental ballistic missile (ICBM). 

BAS: What sequence of events might lead Kim Jong-un to launch a nuclear attack on one of its neighbors like South Korea or Japan? 

SH: I cannot imagine any circumstance that would lead Kim Jong-un to launch an unprovoked nuclear attack on anyone. However, we know so little about him and even less about the military that controls the country’s strategic rocket forces that we can’t rule out a miscalculation or a desperate response to a crisis. It is conceivable that they believe a small nuclear weapon could be used to de-escalate or terminate a conventional confrontation on their terms. 

BAS: How big is the largest nuclear bomb tested by North Korea, and can you give a sense of the level of damage such a bomb would cause? 

SH: The highest yield of the North Korean tests to date is in the range of 15 to 25 kilotons—an explosive power similar to the bombs that destroyed Hiroshima and Nagasaki, causing roughly 200,000 immediate fatalities and lingering radiological health effects for many survivors. If such a weapon were to be exploded over Seoul, it is possible that several hundred thousand people or more would perish. 

BAS: If Pyongyang were to attack South Korea or Japan, what would be the immediate and longer-term effects?

SH: The immediate effects would be horrific, the longer-term effects catastrophic. If several bombs exploded over South Korean or Japanese cities, there could be a million or more casualties. Beyond that, the cities would face massive evacuations and long-term building and grounds decontamination efforts. Dangerous radioactive clouds would drift over South Korea, Japan, China, or Russia, depending on the wind flow. An international order would be destroyed. 

BAS: How close is North Korea to being able to attack somewhere as far distant as the United States with a nuclear weapon? What technical leaps does it need to make to achieve that capability?

SH: I believe that North Korea does not yet have the capability to reach the US mainland with a nuclear-tipped missile. It has a very sparse and not very successful long-range rocket test history, although the missile test on Sunday brings it somewhat closer. Its solid-fueled rockets, which are of greatest concern because they can be launched quickly and from hidden locations, have failed regularly. It will need to miniaturize warheads to a much greater extent than it is currently likely capable of doing, and the warheads will have to survive the stresses at launch and the high temperatures and stresses during re-entry. At the current pace, North Korea may be able to make the technological progress required for a nuclear-tipped ICBM in five or so years. 

One corollary question that one must ask, however, is why would North Korea want to strike the US mainland? It is quite clear that it wants to threaten Washington with such a capability, but to launch would be suicidal, and I don’t believe the regime is suicidal. 

BAS: Besides being able to threaten the United States and its allies, what else could the Kim regime be trying to accomplish with its nuclear weapons?

SH: We need to look closely at how the North’s growing nuclear arsenal may change its domestic policies and foreign relations. Domestically, the nuclear arsenal may help justify the regime’s continued call for sacrifice by its citizens. But it may also provide a more solid foundation for the state’s security, allowing it to devote more resources to economic growth. Foreign visitors have reported that living conditions in Pyongyang have improved markedly in the past few years despite international sanctions. Kim Jong-un has officially promoted the dual policy of military and economic growth. 

Looking abroad, the regime’s nuclear arsenal could make it more aggressive in dealings with South Korea and the rest of the region. We have not seen a return to the North’s especially aggressive behavior of the late 1960s. Nevertheless, being one of fewer than 10 states in the world with nuclear weapons may change Pyongyang’s foreign policy toward its neighbors. And we don’t know how possessing a nuclear arsenal will affect the regime’s behavior in a crisis. 

BAS: Is it plausible that a US pre-emptive strike could destroy all North Korean nuclear weapons, fissile material, and nuclear production facilities? Why or why not?

SH: There is no conceivable way the United States could destroy all North Korean nuclear weapons. It is not possible to know where they all are. Even if a few could be located, it would be difficult to destroy them without causing them to detonate and create a mushroom cloud over the Korean peninsula. 

It is even less likely that the United States could locate and demolish all of the North’s nuclear materials. Missile launch sites could be destroyed, nuclear test tunnels could be bombed, production sites could be destroyed, and North Korean missiles could possibly be intercepted after launch. But North Korea is developing road-mobile and submarine-launched missiles, which cannot be located reliably. New test tunnels can be dug. And while we know North Korea has covert production facilities, we don’t know where they are. The US military may not be able to intercept missiles after launch. The bottom line is, military strikes could be used to set back the North Korean nuclear program but not to eliminate it.

Moreover, I believe the US and South Korean governments consider the consequences of any military intervention unacceptably high—in spite of the proclamation that “all options are on the table.” I believe the military option will only really be on the table if North Korea initiates military actions. 

BAS: There is talk that North Korea is about to conduct a sixth nuclear test. What do you make of these reports? Do you have any insight into what to expect?

SH: North Korea has ample technical reason to test again as it moves toward developing a credible nuclear-tipped ICBM. The test site appears to be ready. I believe the only thing that inhibits them from testing is the political fallout they would face—particularly from China and the new South Korean administration.

BAS: You recently estimated that North Korea has 20 to 25 nuclear weapons. How do we know?

SH: My estimate that it has sufficient plutonium and highly enriched uranium for 20 to 25 nuclear weapons is highly uncertain because we know so little about its uranium enrichment capacity. All estimates are to a large extent based on the observations my Stanford colleagues and I made during my last visit to Yongbyon in November 2010. To my knowledge, no outsiders have been in their nuclear complex since. So the only direct evidence we have is from that 30-minute tour and discussions with their experts at the centrifuge facility. The rest of the estimate is based on indirect evidence—that is, satellite imagery, and what North Korea chooses to publicize, combined with modeling of their capabilities and acquisitions. 

BAS: North Korea carried out its first nuclear test in 2006. How was it able to go from that widely condemned first test to today’s arsenal despite global opposition? 

SH: How they developed a threatening nuclear arsenal despite global opposition is a sad reflection on unwise US policies and the international community’s approach to preventing nuclear proliferation. Controlling the supply side of proliferation has been the predominant international mechanism for halting nuclear weapons development, but it failed terribly in the North Korean case. The international export system is leaky enough that a determined government can develop indigenous bomb-building capabilities over time. In North Korea, this process was exacerbated by the fact that once they built the Bomb, sanctions and isolation allowed them to build a whole arsenal instead of forcing them to give it up.

Insufficient attention has been paid to the demand side—that is, to why states want nuclear weapons and what can be done to influence the decision to acquire them. In the North Korean case, the Clinton administration greatly slowed North Korea’s drive to the Bomb with diplomacy. The Bush administration rejected diplomacy, but was unprepared for the consequences. It stood by while North Korea built a nuclear weapon. Subsequent attempts at diplomacy amounted to too little, too late. (This should serve as a lesson on the Iran nuclear agreement: if you kill a deal, you better be prepared for the consequences). The Obama administration was greeted with a North Korean nuclear test in 2009 and was never able or willing to pursue diplomacy effectively. It relied on two tactics, imposing sanctions and pressuring China, while North Korea continued to build its arsenal. Washington and Beijing never got on the same page on how to deal with Pyongyang. 

BAS: South Korea just elected a new president who takes a more conciliatory approach to North Korea than his predecessor. How might this affect the North’s nuclear activities?

SH: In the end, the Korean peninsula nuclear crisis has to be resolved to the satisfaction of the Korean people. South Korean President Moon Jae-in favors diplomatic engagement with North Korea. I believe that at this point, it is imperative for Seoul and Washington to craft a unified strategy on North Korea and speak with one voice. That voice should reflect the new South Korean president’s views on finding a diplomatic resolution. I hope that the Trump administration will support President Moon, and that Pyongyang won’t pre-empt diplomacy with a nuclear or long-range missile test. 

BAS: If you were advising president Trump, what would you tell him to do in the next month regarding North Korea? In the next six months? The next year?

SH: In the next few weeks, after consultation with President Moon, President Trump should send an envoy to Pyongyang to tackle the most immediate danger—that is, to avoid a nuclear detonation on the Korean peninsula. There is a danger that overconfidence or miscalculation by Kim Jong-un, or an unpredictable reaction to a crisis, could result in a nuclear detonation. I also have serious concerns about a nuclear-weapon accident in North Korea, particularly if Pyongyang feels threatened and begins to deploy its nuclear arsenal. Moreover, in the case of upheaval or chaos in the North, who will control the weapons, and what will become of them? 

The next six months should be followed up with additional bilateral US-North Korea dialogue, with Washington separately keeping Seoul and Beijing informed. Washington should stress the seriousness of the situation, but also listen to the North’s concerns. 

These dialogues may then lay the foundation within the next year for a resumption of multilateral negotiations to halt, roll back, and eventually eliminate North Korea’s nuclear weapons. Talks could also lay the groundwork for normalizing relations between the North and its neighbors and the United States.

Follow CISAC at @StanfordCISAC and www.facebook.com/StanfordCISAC.

MEDIA CONTACTS:

Siegfried Hecker, Center for International Security and Cooperation: (650) 725-6468, shecker@stanford.edu

Clifton B. Parker, Center for International Security and Cooperation: (650) 725-6488, cbparker@stanford.edu

(Amy Zegart, co-director of the Center for International Security and Cooperation, wrote the following essay for The Atlantic.)

Today The Washington Post dropped the bombshell that President Trump had revealed classified information about the Islamic State to Russian Foreign Minister Sergei Lavrov and Russian ambassador Sergey Kislyak when the three of them met at the White House last week. You know a story is big when it gets as many concurrent visitors as the story about the infamous Access Hollywood video. There was no hiding near bushes in the dark this time to walk back the damage. Deputy National-Security Advisor Dina Powell declared the story “false,” and the administration also called out the big guns, with Secretary of State Rex Tillerson and National Security Advisor H.R. McMaster dutifully rushing into the breach to discuss the breach, using oh-so-carefully worded statements about how the president did not reveal “sources or methods” or any “military operations” that were not already known publicly.

So just how bad is the damage? On a scale of 1 to 10—and I’m just ball parking here—it’s about a billion. The story, which has since been confirmed by The Wall Street Journal, The New York Times, Reuters, Buzzfeed, and CNN, notes that the president could have jeopardized a critical source of intelligence on the Islamic State. Not America’s source. Somebody else’s. Presumably from an allied intelligence service who now knows that the American president cannot be trusted with sensitive information.

The type of information Trump cavalierly shared fell under a classification known as “code word,” according to the Post. There are three basic levels of classified information. Confidential information is defined as anything that could reasonably be expected to “cause damage” to American national security if shared without authorization. Secret information is one step up, considered to have the potential to cause “serious damage” if revealed. Top Secret information is a higher classification level still, comprising anything that could reasonably be expected to cause “exceptionally grave damage” to U.S. national security if revealed.

Code word is beyond Top Secret. It limits access to classified information to a much narrower pool of people to provide an extra layer of security. Many secrets are super-secrets—Harry Truman, as vice president, didn’t know about the Manhattan project. He learned of it only after Franklin Delano Roosevelt died and Truman was sworn in as president. Code word classification is so far off the scale, even fake spies rarely refer to it in the movies. Technically, the president can "declassify" anything he wants, so he did not violate any laws. But as Lawfare notes, if the president tweeted out the nuclear codes, he also wouldn't violate the law—but he would rightly be considered unfit for office.

Did Trump reveal intelligence crown jewels or just boast about the fact that he liked diamonds? According to the Post he revealed information about a purported ISIS plot involving laptops. It’s likely, however, that Tillerson, McMaster, the Postand the Times are ALL correct: The president did not reveal sources or methods or military operations. But that doesn’t matter much if he gave away information that will enable the Russians to identify the source or the methods. It looks like he did, since according to the Post’s account he talked about the content of a specific plot, the potential harm, and the location of the city in the Islamic State’s territory where the allied state’s intelligence service detected it. It was almost everything except the GPS coordinates. The denials by Tillerson and McMaster are a classic case of intelligence super-parsing—saying things that are technically and narrowly true but may not be accurate at all. No spin can hide the fact that the breach was deadly serious and reckless in the extreme.

Then there’s the impact on America’s unnamed ally, whom the Post reported was already nervous about sharing such sensitive intelligence with the United States. It is difficult to penetrate the Islamic State, and there is a major risk that this breach will close down a vital source. It’s an even bigger deal in the big picture, potentially jeopardizing intelligence cooperation with other U.S. allies around the world. Trump already raised intelligence eyebrows when he turned his Mar-a-Lago dining area into an impromptu Situation Room after the North Koreans decided to launch a ballistic missile. The president and his aides used the lights on cell phones to illuminate field reports, in full view of resort dinner guests snapping photos. If you’re known as someone who cannot keep a secret, the world’s secret-keepers are not going to tell you much.

“Can you believe the world we live in today?” President Trump said, according to one official in the two Sergeis meeting. “Isn’t it crazy?”

Yes, Mr. President. It’s crazy.

End-stage renal disease makes up 7.2 percent of Medicare spending, even though those patients represent less than 1 percent of the Medicare population, according to a database that tracks chronic kidney disease.

Despite the gnashing of teeth about the runaway costs of Medicare spending, the national health-care system for the elderly, younger people with certain disabilities and chronic kidney disease appears to have found one way to lower costs.

Congress established the end-stage renal disease (ESRD) Prospective Payment System in 2008, as part of the Medicare Improvement for Patients and Providers Act. It mandated that ESRD Medicare patients treat themselves at home if able.

The new payment system introduced two incentives to increase home dialysis use: bundling injectable medications into a single payment for treatment and paying for training for patients to give themselves injections and treatment at home.

A new study by Stanford researchers shows home dialysis treatment among Medicare patients increased by 5.8 percent from January 2006 through August 2013. The researchers also found that non-Medicare patients covered by other forms of health insurance also turned to home dialysis by a jump of 4.1 percent.

“These spillover effects suggest that major payment changes in Medicare can affect all patients with end-stage renal disease,” the authors wrote in the study published in the latest edition of the Journal of the American Society of Nephrology. “One of the stated goals of the PPS payment reform was to incentivize an increase in-home dialysis use, and it appears that it has succeeded in this stated goal.”

Eugene Lin, a postdoctoral fellow in nephrology at the Stanford School of Medicine and lead author of the study, told me that most nephrologists believe the trend toward home dialysis is good for the taxpayers and for the patients.

People going through this phase of chronic kidney disease — when dialysis or a kidney transplant are the only chance of survival  — cost less to take care of at home and have similar outcomes to in-center hemodialysis patients.

“It’s hard to say if one therapy is definitively better than the other,” Lin said, “though home dialysis generally offers patients more independence and potentially better quality of life.”

Lin explained the difference between in-center hemodialysis and home treatment: At a center, blood is filtered through a machine, whereas home dialysis entails either having a hemodialysis machine at home (and having a caregiver help with the treatments) or performing peritoneal dialysis.

The latter is the most commonly used at-home treatment and involves using the abdominal compartment as a filter. The toxins in the blood get filtered through the abdominal membranes into clean fluid, which is then removed and discarded.

Similar drugs are used both in centers and at home, but they’re easier to give in the hemodialysis setting, so had a higher likelihood of overuse prior to payment reform.

“Once they bundled the drug reimbursement with the treatment, we saw dramatic decreases in the use of these drugs and a concurrent increase in home dialysis use,” Lin said.

The researchers, including senior author Jay Bhattacharya of Stanford Health Policy, noted that home dialysis remained stagnant at around 11 percent from 1983 to 1992 and steadily declined until 2008.

“While the cause of this decline is unknown, several policies made home dialysis less favorable than in-center hemodialysis economically,” they wrote.

First, the federal Centers for Medicare & Medicaid Services in 1991 revised its reimbursement policy for the erythropoietin-stimulating agent needed for functioning kidneys, making it the most profitable component of in-centers hemodialysis. Then, CMS introduced a tiered fee-for-service physician payment in 2004, providing the potential for enhanced revenues with in-center dialysis.

But the PPS bundling shifted erythropoietin from the profit side to the cost side, so it was no longer advantageous to use high doses common with in-center hemodialysis, Lin said. This paved the way for an increase in home dialysis use, which is less costly to administer.

Fellows will arrive at Stanford in July to begin the three-week academic training program taught by Stanford faculty, policymakers and thought-leaders in the technology sector.

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Stanford's Center on Democracy, Development, and the Rule of Law is proud to announce the 2017 class of Draper Hills Summer Fellows, which is composed of 28 leaders – selected from among hundreds of applications – advancing democratic development in some of the most challenging corners of the world.

In Bahrain, Burma, Rwanda and Sudan our fellows are working on peace-building initiatives to create more tolerant and inclusive societies. Judges and lawyers are holding government and criminals accountable and reforming the rule of law in Argentina, Guatemala and the Philippines. Gender rights activists are creating new tools and programs to protect the safety and freedom of women and girls in India, Kuwait and Papua New Guinea.

In Egypt, Morocco, Pakistan, Serbia and Ukraine, our fellows are serving inside the government as members of Parliament and senior civil servants to advance reform and new policy agendas. Business leaders in Jordan and India launched initiatives to support more inclusive economic growth and social development.

CDDRL is excited to launch another powerful network of leaders determined to advance change in their communities. They will emerge with new tools, frameworks and connections to enhance their work and deepen their impact on democratic reform.

The 2017 class will mark the 13th cohort of the Draper Hills Summer Fellows Program and the fellows will join the Omidyar Network Leadership Forum, an alumni community of over 300 alumni in 75 countries worldwide.

This is the eighth and last in a series of interviews by the Korea Times on North Korea. CISAC's Siegfried Hecker is featured in this story below by Kim Jae-kyoung:

NK estimated to have ability to produce 7 nuclear bombs a year

By Kim Jae-kyoung

A world-renowned nuclear scientist said that U.S. President Donald Trump must to talk to North Korean leader Kim Jong-un by sending an envoy to Pyongyang to avoid a nuclear catastrophe.

"I believe the first talks should be bilateral and informal by a presidential envoy talking directly to Kim Jong-un," said Siegfried S. Hecker, a senior fellow at the Center for International Security and Cooperation (CISAC) at Stanford University, in an interview.

"I believe both Seoul and Beijing would support such talks. These talks may then also help to build the foundation for renewed multilateral negotiations, which, first and foremost must involve South Korea, as well as China," he added.

Hecker, the co-director of CISAC from 2007 to 2012, has visited North Korea several times to assess the plutonium program at the Yongbyon Nuclear Scientific Research Center since 2004.

He stressed that it is most important to convey the message that nuclear weapons cannot be used under any circumstances.

"There is no such thing as a limited nuclear war. Any explosion of a nuclear device on the Korean Peninsula is a catastrophe of indescribable proportions," he said.

The internationally recognized expert in plutonium science, global threat reduction and nuclear security said that the Trump administration and the new South Korean government face the challenge of avoiding a nuclear detonation on the Korean Peninsula.

He believes that such an incident could result from a miscalculation or overconfidence by the Kim Jong-un regime as well as an accident with the nuclear weapons in the North.

"A conventional confrontation may turn nuclear with an inexperienced leader in charge," he said. "Or, in the case of instability in the North, who will control the nuclear weapons? These are serious concerns that must be addressed now," he added.

Hecker, who served as the director of the Los Alamos weapons laboratory in New Mexico, the birthplace of the atomic bomb, from 1986 to 1997, estimated that North Korea, although he is uncertain, may have sufficient material for 20 to 25 nuclear weapons.

NK's nuclear capabilities evolving 

He explained that the size of its nuclear arsenal depends primarily on how much plutonium and highly enriched uranium North Korea has produced.

"The sophistication of the arsenal depends primarily on nuclear testing. With five nuclear tests conducted over 10 years, North Korea is likely able to produce nuclear devices small enough to fit on missiles that can reach all of South Korea and Japan," he said.

He also estimated that the totalitarian country can produce sufficient plutonium and highly enriched uranium for six to seven bombs per year.

"However, all estimates are uncertain because we know little about the North's capacity to produce highly enriched uranium since it is not possible to monitor such facilities from afar," he said.

In his view, the world does not have to accept the reclusive country as a "nuclear weapons state," but it must be treated as a country with a nuclear arsenal.

"Whether we like it or not, North Korea is a country with nuclear weapons," he said. "The final aim is to have a denuclearized Korean Peninsula, but that will take time. It will have to be done in sequence of halt, roll back and then eliminate."

However, Hecker dismissed North Korea's claim that it has the capability to fire an intercontinental ballistic missile (ICBM) all the way to the U.S. mainland.

"I do not believe North Korea is capable of reaching the U.S. mainland with a nuclear-tipped missile today. It is working on developing such a capability, but it will likely take another five years or so," he said.

Hecker explained that it has not demonstrated all the aspects of necessary rocket technology or the ability to make a nuclear warhead small enough to be able to survive atmospheric reentry.

"Besides, to actually launch a nuclear warhead on an ICBM you must have complete confidence that it will not blow up on the launch pad," he added. "They cannot have such confidence based on their missile launch history."

After the 2012 mass shooting of children and teachers at Sandy Hook Elementary School in Connecticut, a leader of the National Rifle Association proclaimed: “The only thing that stops a bad guy with a gun is a good guy with a gun.”

It would seem that many Californians agreed, according to new research by Stanford Health Policy’s David Studdert and other researchers at academic institutions.

In the six weeks after the Newtown shootings — when a young man fatally gunned down 20 children and six adults — handgun acquisitions in California rose by 53 percent among first-time gun owners over expected levels.

When a couple armed with semi-automatic weapons targeted a San Bernardino County public health event in December 2015, killing 14 people in 2015, handgun purchase rates were 85 percent higher than expected among residents of the city of San Bernardino and adjacent neighborhoods, compared with 35 percent higher elsewhere in California.

In a new study in the Annals of Internal Medicine, lead author Studdert, a professor of medicine at Stanford Medicine and professor of law at Stanford Law School, writes that their findings have implications for public health as firearm ownership is a risk factor for firearm-related suicide and homicide.

“There is strong evidence linking gun ownership to risks of gunshot injuries, so any sudden boost in firearm ownership could have public health implications,” Studdert said. On their own, these two mass shootings are unlikely to have caused enough of a change in ownership patterns to have significant public health effects.

“But over time, purchasing responses to a succession of unnerving events like this — from mass shootings to terrorist attacks, to elections — could change levels of gun ownership enough to increase overall rates of gun injury and death.”

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The authors write that for some, mass shootings may induce repulsion at the idea of owning a weapon. But for others, they note, it may motivate acquisition.

“Mass shootings are likely to boost sales if they heighten concerns over personal security because self-protection is the most commonly cited reason for owning a firearm,” they said.

More than 32,000 people die of gunshot wounds in the United States each year, according to the Centers for Disease Control and Prevention. While mass shootings account for less than 1 percent of those deaths, they are the most visible form of firearm violence because of the extensive broadcast and social media coverage that surround them.

Using detailed individual-level information on firearm transactions in California between 2007 and 2016, the researchers analyzed acquisition patterns after two of the highest-profile mass shootings in U.S. history. They found large and significant spikes occurred among whites and Hispanics, and among individuals who had no record of having previously acquired a handgun.

Although these spikes in handgun purchases after both mass shootings were large, they were also short-lived and accounted for less than 10 percent of annual handgun purchases statewide.

“Concerns about firearm violence and the public health risks of firearm ownership should stay focused on the much larger volume of weapons that routinely changes hands, and the immense stock that already sits in households,” write Studdert and his colleagues, Stanford Health Policy researcher Yifan Zhang, PhD; Jonathan Rodden, PhD, a professor of political science at Stanford; Rob J. Hyndman, PhD, a professor of statistics at Monash University in Australia; and Garen J. Wintemute, MD, MPH, an expert on gun violence at the University of California, Davis.

“On the other hand, the cumulative effect of such ‘shocks’ as Newtown and San Bernardino shootings on firearm prevalence may be substantial,” they write. “Moreover, firearm acquisitions seem to be sensitive to a range of other events that are also common, such as federal elections, new firearm safety laws, and terrorist attacks.”

Taken as a whole, they said, these events may drive significant increases in overall firearm prevalence, which may, in turn, increase the risk for firearm-related morbidity and mortality in the long run. The authors urge further research should explore the cumulative effects and temporary shifts in acquisition patterns, their causes, and their implications for public health, crime and social cohesion.