How Fast Will North Korea’s Nuclear Arsenal Grow?

This article originally appeared in the May 2015 issue of The Diplomat magazine. Subscribe to The Diplomat here.

Recent weeks have seen growing alarm over North Korea’s nuclear program. This month, numerous senior U.S. military officials said that Washington believes North Korea has the ability to strike the western United States with a nuclear-tipped KN-08 intercontinental ballistic missile. “Our assessment is that they have the ability to put a nuclear weapon on a KN-08 and shoot it at the homeland. We assess that it’s operational today,” William Gortney, commander of the North American Aerospace Defense Command (NORAD) told reporters.

The Wall Street Journal reported that Chinese experts believe Pyongyang has already amassed twenty nuclear warheads, and could double that number within a year. That report came on the heels of a widely discussed report by the U.S.-Korea Institute at the Johns Hopkins School of Advanced International Studies (SAIS), which assessed that North Korea could drastically expand the size of its nuclear arsenal over the next five years.

Specifically, in its most dire forecast, the SAIS report suggested that North Korea could expand its nuclear arsenal from 10-16 nuclear warheads today, to as many as 100 warheads by 2020. The report’s mid-range forecast was that North Korea will have 50 nuclear warheads in five years’ time, while its low-end estimate is that Pyongyang will have just 20 bombs in 2020.

These revelations have greatly unnerved regional analysts. Indeed, in a recent article on The Diplomat, Robert Kelly argued that if North Korea’s nuclear arsenal keeps expanding, South Korean leaders may need to consider a preemptive strike to destroy Pyongyang’s strategic weapons.

The concerns are largely overblown, however. There is little reason to think that North Korea will greatly expand the size of its nuclear arsenal in the near future. But even if Pyongyang were to do so, South Korea would be foolish to try a preemptive strike.

Slow and Steady

Although North Korea’s growing uranium-enrichment capabilities enhances its ability to produce more nuclear warheads, there are compelling reasons to think North Korea will not drastically increase the size of its arsenal in the coming years.

To begin with, such a rapid buildup would be completely at odds with the history of North Korea’s nuclear program, which has proceeded at a snail’s pace. North Korea began seeking nuclear weapons at least as early as 1980, but didn’t test its first device until 2006 – some 26 years later. Nothing has changed in the nine years since. As noted above, North Korea likely only has 10 nuclear warheads in its arsenal, and 20 at most. Since that first test, then, it has been producing nuclear weapons at a pace of no more than 2.75 bombs a year, and possibly as few as 1.5 annually (factoring in the two warheads used in the 2009 and 2013 tests) To suggest that North Korea may suddenly start building twenty warheads of year ignores the entire history of Pyongyang’s nuclear program.

Moreover, despite its increased enrichment capabilities, a number of factors are likely to constrain North Korea’s nuclear buildup in the near future. For one thing, North Korea remains an appallingly poor country, and this is the greatest threat to the regime. Indeed, Kim Jong-un’s overarching governing agenda (called the “byungjin line”) is built on the simultaneous development of nuclear weapons and the economy.

The latter is hardly an afterthought. While the North Korean government has adamantly refused to surrender its nuclear stockpile in exchange for economic incentives, Kim Jong-un has advanced bold economic reforms (by North Korea standards, at least) during his short time in power. This includes more aggressively seeking out international investors and promoting tourism. His regime has also begun decentralizing farms and allowing individual farmers to keep more of their crops. Some have compared these agricultural reforms (called the “June 28 measure”) to the ones China adopted in 1987. The June 28 measure was soon deepened and expanded to apply to other industries under the “May 30 measure.” Perhaps most significantly, the North Korean government has been establishing special economic zones at a feverish pace, with no fewer than 19 new SEZs announced since 2013.

These reforms are already paying dividends. In recent years, the UN Food and Agricultural Organization (FAO) has assessed that North Korea’s food security is improving. Moreover, after years of annual contraction, since 2011 the Bank of Korea (South Korea’s central bank) has reported that North Korea’s economy has begun growing. This has forecast modest growth rates for North Korea in the coming years, after years where North Korea’s economy contracted annually. This economic growth appears to be accelerating; South Korea’s Hyundai Research Institute predicts that North Korea’s economy will grow by 7 percent in 2015.

All this suggests that Kim Jong-un sees improving the economy as crucial to shoring up his regime. In particular, he likely sees improving the livelihoods of the country’s elite as essential to staying in power. Indeed, the worsening economic situation was a central reason that Kim Jong-il was never able to achieve the popularity of North Korea’s founder and eternal president, Kim il-Sung. Kim Jong-un has tried to emulate Kim il-Sung since he first entered the public spotlight, and improving North Korea’s economy is one aspect of this.

Kim Jong-un’s need to improve the economy constrains his ability to rapidly expand the size of North Korea’s nuclear arsenal. To begin with, as the SAIS report indicates, a rapid expansion of North Korea’s nuclear arsenal will require frequent nuclear tests. These tests, however, invite swift international retribution, including from North Korea’s primary patron, China. Frequent nuclear tests would also cripple Kim Jong-un’s efforts to improve relations with Russia.

In addition, rapidly expanding North Korea’s nuclear arsenal would be prohibitively expensive. In fact, it is not only expensive to build the actual nuclear warheads, but also to maintain a nuclear enterprise. The costs of this latter, of course, increase significantly the larger a country’s nuclear arsenal becomes. In 2011, for example, Global Zero estimates that North Korea spent about $700 million on its nuclear program. Meanwhile, Pakistan – which is believed to have between 90-110 nuclear warheads – is believed to spend at least $2.2 billion on its nuclear arsenal annually, and possibly as much as $2.5 billion. This would be a huge chunk of North Korea’s overall military spending, which is around $9 billion a year, according to South Korea’s state-run Korean Institute of Defense Analyses.

As this suggests, besides the economic factors, there are important strategic constraints on North Korea’s ability to rapidly expand the size of its nuclear arsenal. First among these is the tradeoff between its nuclear weapons program and its conventional military capabilities. That is, as in other nuclear countries, expanding North Korea’s nuclear program would come at the expense of its conventional capabilities.

This is important because North Korea maintains the fourth largest military in the world. Moreover, North Korea appears to have undertaken something of a military modernization program, particularly in the realm of naval warfare. As Joseph S. Bermudez Jr. notes, “Since the early 2000s the Korean People’s Navy has undertaken both a small-scale shipbuilding program and a series of upgrades to a number of its existing vessels and weapon systems.” Although this began under Kim Jong-il, Bermudez believes it has accelerated since Kim Jong-un assumed power. It would make little sense to begin these modernization programs if nuclear weapons development were going to consume much of the defense budget in the years ahead.

There are other strategic constraints on North Korea’s ability to rapidly expand the size of its nuclear arsenal as well. Most notably, for the foreseeable future, North Korea is almost certainly going to be more concerned with making qualitative improvements to its nuclear weapons arsenal, rather than simply trying to build up the number of nuclear weapons it possesses.

Indeed, despite common belief, as well as the country’s own constant boasts to the contrary, North Korea is not currently a nuclear weapons state. At best, North Korea’s nuclear enterprise has demonstrated that, if given weeks to prepare, it can probably conduct a nuclear explosion. Even this may be an overly generous interpretation. Before its first nuclear test in October 2006, for example, North Korea reportedly informed China that it would explode a four-kiloton nuclear device, was itself shockingly small. By way of comparison, CNN noted shortly after that India and Pakistan’s 1998 nuclear tests registered around 15-kiloton yields, and America’s first nuclear test in 1945 produced a 20-kiloton yield. North Korea nonetheless failed to achieve even this relatively modest goal as the resulting nuclear denotation was estimated to have produced just a 0.48-kiloton yield.

North Korea’s second nuclear test was only slightly more successful, producing a 2.35 kt yield, according to an estimate later published in the Bulletin of the Seismological Society of America. Even this was a matter of some dispute, however. A Congressional Research Service report later noted that, “Unlike its first test, in 2006, there is no public record that the second one released radioactive materials indicative of a nuclear explosion.” The U.S. Intelligence Community would only say that North Korea “probably conducted” a nuclear test. After assessing the different possibilities, Jeffrey Park, a Yale geology professor, said the most likely explanation was that “North Korea tried and failed to get a simple plutonium bomb to detonate correctly.”

North Korea’s third nuclear test in 2013 was by far the most successful, producing a yield of somewhere between 7-15 kt, with perhaps the best estimate pegging the yield at 12.2 kt. Still, this was at best equal to India and Pakistan’s 1998 nuclear tests, and almost certainly below it.

In any case, none of this suggests that North Korea is a nuclear weapons state. As noted above, these tests occurred only after weeks of careful and unimpeded preparations, which are hardly the conditions North Korea could realistically expect during wartime.

In fact, Pyongyang faces a number of remaining obstacles before it can boast of having deployable nuclear weapons. Perhaps the most pressing (and certainly the most discussed) is miniaturizing a nuclear warhead so it can be placed on one of North Korea’s missiles. Although the U.S. said earlier this month it is operating under the assumption that Pyongyang has acquired this capability, this assessment is based on an abundance of caution. It is widely doubted by experts, and North Korea has notably has not demonstrated this capability.

Miniaturizing a nuclear warhead isn’t the only obstacle must overcome. As Jeffrey Lewis (who believes North Korea probably has all the requisite capabilities) noted in a recent article, there are at least two other obstacles Pyongyang must overcome. First, it has to design a nuclear warhead that can withstand the “shock, vibration and temperature change” it will encounter in flight. Second, it must design reentry vehicles that can withstand the scolding temperatures it will encounter when it reenters the atmosphere. This is a challenge that other countries like China struggled to overcome.

Even once these obstacles are surmounted, there are a few additional challenges North Korea will have to overcome. The first, of course, is achieving technical reliability for both its warheads and missiles. Even if North Korea is able to demonstrate all the necessary technological achievements in a single test, Pyongyang will need to ensure it can replicate this success on a reliable basis. If the past is any guide, North Korea is likely to struggle immensely with this as well. In fact, a recent widely quoted assessment noted, “The challenges Pyongyang faces in developing new delivery systems over the next five years and beyond are likely to be greater than those encountered in its nuclear program.”

Second, even after North Korea weaponizes its nuclear capabilities, it will need to operationalize them, which “refers to command and control mechanisms, coordination procedures between scientific and military agencies, and training protocols in the military to deploy and explode weapons.” As Gaurav Kampani, a non-resident fellow at The Atlantic Council, noted in a path-breaking article on the subject, “If the weapon systems constitute the hardware, operational routines make up the software that enables use of weapons during war.” North Korea is likely to struggle with this aspect of becoming a nuclear weapon state. As Kampani notes, the gap between weaponization and operationalization has increased dramatically in the modern atomic era. Whereas it took the P5 states (the United States, Russia, the United Kingdom, France and China) an average of four months to operationalize their nuclear weapons, it has taken the nuclear weapon states since an average of four years to do so.

It is these weaponization and operationalization challenges that are likely to consume the bulk of the North Korean nuclear enterprise’s attention in the coming years. After all, what’s the point of building a ton of warheads if you cannot use them?

Living With a Nuclear North Korea

At some point in the future, however, North Korea is likely to overcome these challenges and build a much larger nuclear weapon stockpile. This situation would not be catastrophic for South Korea, however, and – counter intuitively – may even be preferable to Pyongyang possessing a small nuclear arsenal.

As Robert Kelly noted in his article on The Diplomat, the superpower nuclear balance was least stable during the early Cold War when both sides lacked a second-strike capability. That is, they lacked the ability to absorb a surprise attack and retaliate with overwhelming nuclear force. This created both a temptation to launch a first strike against the enemy, as well as a “use-them-or-lose-them” mentality. The situation stabilized once the superpowers acquired a second-strike capability by expanding the size of their arsenals and diversifying their delivery systems. Among other things, second-strike capabilities reduce the chance of leaders making rash decisions based on incomplete or false information during crisis environments.

Kelly maintains, however, that North Korea will never acquire a second-strike capability primarily because of its small size and low technological base. As he puts it, “North Korea is too small to pursue the geographic dispersion strategies the Soviets tried, and too poor to build a reliable SLBM force or effective air defense.”

This is almost certainly false, however. The U.S is already operating on the assumption that North Korea has road-mobile ICBMs in the form of the KN-08, which can be moved around to elude the enemy. With a decently sized arsenal of road-mobile nuclear missiles, the United States and South Korea could not be confident that they would be able to successfully destroy all of North Korea’s nuclear weapons in a decapitation strike. Indeed, as NORAD commander Admiral Bill Gortney admitted of the KN-08: “It’s the relocatable target set that really impedes our ability to find, fix and finish the threat.” He added that this problem is compounded by America’s limited ISR capabilities in North Korea. America and South Korea’s confidence would be weaker still if North Korea acquires submarine-launched ballistic missiles, which it is believed to be pursuing.

There are a number of important differences between North Korea today and the situation the U.S. and Soviet Union faced during the Cold War. First, for the United States and Soviet Union, acquiring a second-strike capability meant building an arsenal that could survive a massive nuclear attack. Since South Korea doesn’t possess nuclear weapons, and the United States would be unlikely to use nuclear weapons except in retaliation, Pyongyang’s arsenal only needs to be able to survive a conventional attack. This significantly increases survivability. For example, despite being nearly six times as small as North Korea, Israel has been content with a small nuclear arsenal because it doesn’t have any nuclear-armed adversaries.

Second, since – as Kelly himself notes – the United States and Soviet Union were many times larger than North or South Korea, they needed many more nuclear missiles to survive a first strike in order to be able to launch a massive retaliation against the other. But, as Kelly points out, South Korea is many times smaller than the United States and Soviet Union, and the bulk of its population is concentrated in five cities. As a result, to achieve a second-strike capability, North Korean leaders would only need to be confident a few nuclear warheads would survive a first strike.

Kelly also argues that because of their country’s vulnerability to a small nuclear attack, South Korean leaders will launch a decapitation strike rather than allow North Korea to expand its arsenal. As he puts it: “Both the Soviet Union and the United States were so large, that only a massive first strike would have led to national collapse. In South Korea by contrast, nuking only about five large cities would likely be enough to push South Korea toward national-constitutional breakdown.”

There are at least two issues with this argument, however. First, given that only a few nuclear weapons would be necessary to threaten South Korea’s existence, it’s not clear why South Korean leaders can tolerate a small North Korean nuclear arsenal, but would launch a preventive attack to prevent it from expanding. Second, while many more nuclear weapons are necessary to pose an existential threat to large countries like the United States and Russia, both the U.S and Soviet Union did indeed build nuclear arsenals large enough to do just that. Thus, South Korean leaders would only have to live with the same balance of terror that characterized the Cold War.

It’s virtually certain that they will choose to do so rather than carrying out a preventive strike to destroy North Korea’s nuclear arsenal. Such an attack – which the U.S. would almost certainly refuse to participate in – would be incredibly risky.

To begin with, South Korea would likely fail to destroy North Korea’s entire nuclear arsenal. If only a few nuclear missiles survive the attack, North Korea would respond with the devastating nuclear strikes South Korea would have attacked to prevent. Even in the unlikely event that South Korea did successfully destroy all of North Korea’s nuclear weapons, Pyongyang’s artillery and other conventional weapons would ensure an enormous counterattack. This alone is enough to deter an attack.

In fact, as Kelly notes, the United States and South Korea have considered attacking North Korea in the past, such as during the 1994 nuclear crisis. They ultimately decided against doing so because of North Korea’s conventional military capabilities. As Don Oberdorfer notes in The Two Koreas, during the 1994 crisis “U.S. estimates were that in case of war, North Korea could pound Seoul with five thousand rounds of artillery within the first twelve hours, causing havoc, death, and destruction in the capital.” Oberdorfer also reported that American military planners believed a war with a non-nuclear North Korea in 1994 “would cost 52,000 U.S. military casualties, killed or wounded, and 490,000 South Korean military casualties,” to say nothing of civilians.

In other words, the only thing worse than living with a nuclear North Korea could be trying to disarm it through force. That was certainly the judgment of American leaders in the 1950s, when they briefly considered (and quickly rejected) a preventive strike to eliminate the Soviet Union’s nuclear arsenal before it was capable of threatening the United States directly. South Korean leaders will be forced to the same conclusion, however painful it may be.