From the Vault: Nuclear Calculus

Editor’s Note

Due to recent events in Iran, I am making excerpts from our September 2017 internal research report on North Korea publicly available. While this analysis was written during the height of tensions between the United States and North Korea, I believe this report remains highly relevant for understanding current geopolitical dynamics for several key reasons:

First, it explains the history and strategy that North Korea used to become a nuclear power, providing crucial context for how a small, isolated nation successfully developed nuclear weapons despite decades of international opposition.

Second, it illuminates why North Korea’s strategy seemingly worked without provoking a US military response, while Iran’s push to become a nuclear power has been met with military action. The report explains how North Korea’s conventional deterrent — particularly its ability to devastate Seoul — and geographic advantages created costs for US military intervention that Iran simply does not possess, making military action against Iran a more viable option.

Third, it explains important nuances between developing a nuclear device and a deliverable nuclear weapon, distinctions that remain critical for assessing any nation’s true nuclear capabilities and the timeline for when they might pose a genuine strategic threat.

Fourth, it helps explain why President Trump chose inaction against North Korea in his first term but has chosen action against Iran. The analytical framework reveals how different geographic, conventional, and alliance structures create vastly different strategic calculations for US decision makers.

Finally, the strategic framework and underlying dynamics outlined in this report remain highly relevant for understanding both North Korea’s success in becoming a nuclear power and Iran’s current challenges in attempting to do the same.

Nuclear Calculus: North Korea on the Brink (Excerpts)

September 2017

A Model for Forecasting Geopolitics

Geopolitics describes the complex system of interconnected relationships between societies. The interaction between nations within this system is driven by their imperatives and constraints. Imperatives are the things that must be accomplished in order for a community to survive and prosper, while constraints are the things that a society is prevented from doing.

Understanding a country’s imperatives and constraints provides essential context for interpreting its behavior. This perspective not only clarifies why nations act as they do, but also helps anticipate future actions and potential outcomes of conflict.

Often, a nation’s constraints hinder its ability to fulfill its imperatives. Conflict arises when one country’s pursuit of its imperatives collides with those of another. In such cases, each side seeks to strategically constrain the other.

North Korea’s overriding imperative is the long-term survival of the ruling regime. Its key constraints are geographic and strategic: it is a small, isolated country surrounded by major powers capable of overwhelming it militarily. Its reliance on regional benefactors for economic and military support further exposes its vulnerability. All of North Korea’s behavior, as discussed in this report, can be traced back to this interplay of imperatives and constraints.

The core challenge for North Korea has always been securing regime survival while remaining vulnerable to powerful adversaries whose own imperatives may threaten that goal. As a result, North Korea has sought to raise the cost any foreign power would incur in acting against it — thereby deterring threats and reinforcing its own security.

George Friedman, founder of Stratfor and Geopolitical Futures, explains how these constraints have driven North Korea’s geopolitical strategy, “North Korea believed their position was strategically impossible. They faced three major powers, any of which could annihilate North Korea. Their strategy was to avoid annihilation by proving it would not be worth anyone’s trouble. This did not mean being meek by any stretch. It required convincing other powers that they would incur a huge cost by absorbing or defeating North Korea. The country’s greatest strength was its relative unimportance. If it could also increase the dangers involved in being subdued, it could survive.”

We can examine North Korea’s predicament using Game Theory[1], which provides a model for forecasting the evolution of conflict by predicting the strategy that an actor will pursue to achieve its imperatives while navigating the other side’s attempts at restraint. Taking a game theory approach, we can define the formula that ensures North Korea’s security from a foreign enemy:

Level of pain North Korea can inflict > benefit a foreign country receives from conflict with North Korea

The level of pain North Korea can inflict on an enemy can be separated into three components.

1. The commitment of a regional benefactor to defend North Korea

2. The amount of destruction North Korea can inflict on the enemy and/or its allies

3. The willingness of the foreign leader/public to accept military conflict

When North Korea invaded the South to start the Korean War, its leaders were stunned by the speed and force of US intervention. They had misjudged the US’ strategic imperatives by failing to anticipate that the US would view halting the spread of communism as a vital national interest worth going to war over, even in a distant part of the world. North Korea assumed the “cost” it could impose through military force would outweigh any potential “benefit” the US might see in intervening.

But miscalculations occurred on both sides. Kim Il Sung, grandfather of Kim Jong Un, had been installed by the Soviets and believed he had the implicit backing of both the Soviet Union and China. Meanwhile, US military leaders, particularly General Douglas MacArthur, wrongly assumed that Beijing and Moscow would stay out of the conflict due to fear of US nuclear capabilities.

As the Cold War progressed and the Soviets joined the US as a nuclear power, their support for North Korea shifted from implicit to explicit. This transformed the strategic calculus: the cost of US intervention in North Korea now carried the potential risk of nuclear escalation. (While the Soviets had tested a nuclear device around the time of the Korean War, it was not a viable weapon because they lacked a viable delivery system, limiting its deterrent value at the time.)

Everything changed with the collapse of the Soviet Union. Without their primary benefactor, the Kim regime became newly vulnerable. The US regained a strategic advantage once North Korea lost its most significant deterrent: the threat of nuclear retaliation backed by a superpower. North Korea recognized that the cost of US intervention (whether militarily, covertly, or diplomatically) had fallen dramatically. In response, the regime began taking steps to raise the potential cost of foreign aggression, in order to ensure its survival.

The first phase of this strategy involved drawing closer to China, seeking to replace the deterrence once provided by the Soviets. But this alignment was always seen as a short-term solution. The fall of the Soviet Union taught North Korea a vital lesson: relying on allies for security carries unacceptable risk. Consequently, the regime set a long-term goal of reducing dependence on foreign patrons, especially China and Russia, for several reasons:

1. Instability in an ally threatens your own security: If China were to collapse like the Soviet Union, North Korea’s regime would face existential risk.

2. Dependency breeds subservience: The Kim family has a deep aversion to subordinating itself to any outside power.

3. Allies cannot be trusted to come to your aid: During the Korean War, China encouraged North Korea’s invasion and pledged support, but refused to intervene when the US entered the war. Only after American forces approached the Yalu River — and thus China’s own border — did Beijing act, and even then, it only offered support in situations that protected Chinese interests.

4. China’s interests evolved: Once a revolutionary power hostile to the West, China became increasingly integrated into the global economy. North Korea logically concluded that Beijing’s economic ties to the US and its allies would, eventually, outweigh its ideological loyalty to Pyongyang.

North Korea’s goal was to survive the collapse of the Soviet Union and decrease any ideological dependency that remained with China. To accomplish this, the regime adopted a strategy centered on persuading the world of three, at times contradictory, ideas:

1. That North Korea is dangerous and capable of devastating retaliation: By projecting overwhelming and unpredictable military power, the regime sought to deter any foreign attempt at intervention or regime change.

2. That the regime is irrational and potentially suicidal: To this end, North Korea was successful. Feeding generals to a pack of wolves and shooting them with anti-aircraft guns for the slightest indiscretion is an effective strategy to convince people that you are a homicidal maniac. It is also not surprising that these random, maniacal acts of violence are some of the only information that emerges from the hermit kingdom. In all likelihood, these acts were intended for propaganda purposes. Yet, whether or not these stories are exaggerated or staged for effect, they have proven effective in reinforcing the image of a leadership unbound by reason. This uncertainty forces adversaries to consider the terrifying possibility that any provocation might trigger an unpredictable, self-destructive response. Even if other nations suspected it was a facade, the risk of miscalculation was too high to ignore.

3. That the regime is fragile and on the brink of collapse: Paradoxically, North Korea also portrayed itself as weak and unstable. This narrative suggested that there was no need to take the risks necessary to replace the regime when it was likely to be ousted by its own people at any moment. By convincing the world that they were weak, and that the regime could topple at any point, Pyongyang discouraged external action by making it seem unnecessary and excessively risky.

George Friedman explains, “A nuclear program firing random ballistic missiles, insane threats, and evidence of extraordinary poverty and political instability all combined to prevent any action that someone might want to take, assuming anyone wanted to take action. North Korea appeared to be powerful, quite mad, and about to collapse. These are incompatible notions, but they gave everyone good reasons not to attack. Those who feared North Korea, those who believed North Korea was a lunatic bin, and those who felt North Korea was close to collapsing all drew the same policy conclusion: Do not attack North Korea. It was a brilliant ploy, and a regime that had no business surviving the 1990s did.”

North Korea could fool the world into believing they were crazy and on the verge of collapse but their ability to convince the world that they were dangerous had to be based in reality. Yet this presented a significant challenge. Without a powerful benefactor like the Soviet Union, and constrained by its small size and limited resources, North Korea lacked the capacity to build a military capable of confronting a superpower like the United States directly.

Instead of preparing for a conventional war with the US, North Korea adopted an indirect strategy: threatening the security of a key American ally, South Korea. The core of its deterrence doctrine became the ability to inflict massive civilian casualties on the South in the event of US attempts to overthrow the regime. This strategy did not require victory in a full-scale war, only the ability to raise the cost of intervention beyond what the US was willing to bear.

When Kim Jong Il assumed power in 1994, he formalized this approach through a policy known as Songun, or “military-first.” As South Korean scholar Han S. Park explains, “the military is not just an institution designed to perform the function of defending the country from external hostility, instead, it provides all of the other institutions of the government with legitimacy.” The regime concluded that even amid economic collapse, prioritizing the military was essential to its survival. In this logic, a well funded military served both as a deterrent abroad and a foundation of domestic control.

The Songun policy has turned much of the North Korean economy into a weapons factory. As a result, North Korea has built up an impressive arsenal of conventional weapons, such as artillery and short-range rockets. (It should also be stated that North Korea had a thriving economy during the Cold War as a result of trade with the Soviet bloc and their allies. In fact, the North Korean economy was larger than the South until the 90s).

North Korea’s deterrence strategy also benefits from two major geographical advantages, which significantly increase the lethality of its conventional weapons and raise the cost of intervention far beyond what is typical elsewhere.

First, the South Korean capital of Seoul, home to 25 million people, is only 30 miles from the North Korean border and is within range of North Korea’s artillery and short-range rockets. In fact, half of South Korea’s population lives within range of these weapons. In contrast, the North Korean population centers, including Pyongyang, are further from South Korea and close to its Chinese border.

The second geographical advantage is that North Korea is mountainous while the population centers in South Korea are flat. North Korea has built tunnels and bunkers for their missiles and artillery that protect them from aerial assault. These weapons can be quickly fired and then rolled back into their impenetrable mountain bunkers.

Both sides understand that North Korea would eventually be defeated in a full-scale war with the United States. However, by the time US forces could neutralize North Korea’s conventional weapons, tens of thousands of civilians in Seoul would likely be dead. This grim reality forms the backbone of North Korea’s conventional deterrence.

Yet the Kim regime also recognized that a strategy based solely on threatening South Korea left it vulnerable in several ways. First, its artillery based deterrent could only credibly target South Korea and US forces in the region but not the US homeland. Second, it left the regime exposed to the possibility that the US might one day accept the cost of intervention. Recognizing this vulnerability, North Korea concluded that only nuclear weapons could deter all potential adversaries and elevate its strategic position against a superpower like the United States.

Understanding this strategic imperative, North Korea moved quickly to develop the nuclear capabilities that conventional weapons alone could not provide. Following the collapse of the Soviet Union, North Korea began smuggling plutonium from Russia. By the early 1990s, it had started enriching that plutonium for potential use in a nuclear device. In 1993, North Korea withdrew from the Non-Proliferation Treaty (NPT), which bans non-nuclear states from pursuing nuclear weapons programs. This move sparked the first in a series of nuclear crises between North Korea and the United States.

That initial crisis was eventually resolved in 1994, when the Clinton administration negotiated the Agreed Framework. Under the deal, North Korea pledged to dismantle its nuclear reactors and allow international inspections in exchange for economic aid and diplomatic normalization. However, North Korea quickly reneged on its commitments.

As a result of this crisis, the regime learned several valuable lessons that would serve as the basis for their long-term nuclear strategy.

First, North Korea realized that the US was willing to negotiate temporary agreements rather than take military action. In Dancing with the Devil, author Michael Rubin gives a detailed analysis of more than half a century of US attempts to engage and negotiate with North Korea. It’s a sobering account, and one thing becomes clear: every administration has made it obvious that there is little to no political will to initiate a war with North Korea, given the catastrophic consequences it would bring to South Korea. Michael Rubin explains, “It is easy to play the part of the blame game, but North Korea’s development of nuclear weapons and slow progress on the means to deliver them to US territories like Guam, Hawaii, Alaska, and the US West Coast is a testament to decades of diplomatic and strategic failure on the part of almost every US administration, regardless of party.” After watching one administration after another choose diplomacy over force, Pyongyang has little doubt that they hold the upper hand in these negotiations, and they have taken full advantage of their dominant position.

Second, North Korea understood that they were not close to developing a deliverable nuclear weapon. A nuclear weapons program takes time and much of the process cannot be hidden from the world. Therefore, North Korea realized that they must build their program incrementally. While they consistently worked on the steps that could be done covertly, much of the process cannot be done in secret, such as detonation and ballistic missile tests. North Korea decided that these critical components would be undertaken in increments and in full view of the world. These steps were too visible to go unnoticed and inevitably triggered international alarm. When tensions escalated to the point where military intervention became a real possibility or sanctions began to take effect, the regime would agree to terms that paused further development but never reversed the gains it had already made. Thus, at each stage North Korea would move closer and closer to obtaining a deliverable nuclear weapon.

Finally, North Korea learned the importance of choosing to advance their nuclear weapons program at the most politically inopportune time for a US President to act militarily.

There have been six nuclear crises, relating to North Korea’s production/testing of a nuclear device or ICBM delivery system:’93, ’98,’01,’06, ’09, and ’17.[2] Notably, every single president since Clinton has been forced to deal with a North Korean crises their first year in office (’93,’01,’09,’17). North Korea astutely realized that a new president is more interested in pushing through their policy agenda rather than starting a pre-emptive war with North Korea. Only twice have the crises occurred outside of a US President’s inaugural year; however, ’98 coincided with President Clinton’s impeachment and in ’06 the US was bogged down in Iraq and President Bush was running for reelection. Thus, every single crisis has occurred when a US President was hamstrung from initiating military action. This gave North Korea a window to advance its weapons program for a year or more at a time before the West could mount a serious response. By choosing their timing carefully, they not only minimized the chance of a military response by the US but also maximized the time they had to test and develop their weapons system before they would agree to a favorable diplomatic solution.

This pattern reveals the sophisticated nature of North Korea’s strategic planning. Rather than random provocations by an unstable regime, these carefully timed crises demonstrate North Korea’s deep understanding of American political cycles and their ability to exploit predictable periods of US political vulnerability to advance their nuclear program with minimal risk of military retaliation.

It should be emphasized that the key to the implementation of North Korea’s gradual progression strategy is the threat that North Korea’s conventional weapons pose to South Korea. This conventional capability, combined with its broader “dangerous, crazy, weak” strategy, significantly raises the cost of US military intervention. That, more than anything else, explains why North Korea has been able to advance its nuclear program over decades, while other so-called rogue states (such as Iran, Iraq, and Libya) have been thwarted.

Countries like the United States and Israel have historically been willing to use military force to prevent adversaries from acquiring weapons of mass destruction, particularly when those adversaries lacked the ability to meaningfully retaliate. Iraq is a clear example. Despite its proximity to Israel and its stockpile of conventional weapons, Iraq was never able to pose a credible deterrent. Its rockets and artillery were exposed to aerial assault and were quickly neutralized by US airstrikes at the start of the Iraq War.

North Korea presents a fundamentally different challenge. Its conventional weapons — primarily artillery — are buried in fortified bunkers carved into mountains, making them highly resistant to aerial attack. These systems are exposed for only brief moments while firing, giving US forces a narrow and uncertain window to strike. While the US could eventually neutralize these positions, it likely could not do so before they inflicted catastrophic damage on Seoul and other densely populated areas of South Korea.

In a statement released through the state-run Korean Central News Agency in 2016, Kim Jong Un made it clear that the lesson he learned from the Iraq War was that without a nuclear deterrent a small country, like North Korea, will always be vulnerable. “The Saddam Hussein regime in Iraq and the Gaddafi regime in Libya could not escape the fate of destruction after being deprived of their foundations for nuclear development and giving up nuclear programs of their own accord.”

North Korea’s Nuclear Capabilities

There is a great deal of confusion regarding North Korea’s nuclear capabilities, yet a proper assessment is essential to understand the current crisis.

There are three stages of development needed to build a deliverable nuclear bomb. The first stage is the development of a nuclear device, which is a system that can be tested in a fixed environment but is not mechanically stable, rugged, or small enough to be a weapon. This is the easiest step. Assuming you have enriched uranium or plutonium, a college student can design a basic nuclear device.

This is the only stage that we know with certainty that North Korea has completed.

The second step is to turn the device into a warhead. This requires miniaturizing the device so that it is small enough to fit to a missile, rugged enough to withstand the volatile conditions aboard the missile, and a trigger that can detonate at exactly the correct moment and precise enough to create a chain reaction. This step is significantly more difficult than the first.

George Friedman explains, “The difference between a nuclear device and a nuclear weapon is that the former is an undeliverable system, nested in a framework designed to maximize the chance of detonation. A bomb, on the other hand, can destroy a city.

The distance between a device and a bomb is substantial. A bomb must be small enough so that it can be fitted into a delivery system. It must also be robust enough to be placed in the delivery system without breaking. A device is not usually robust, and therefore nuclear weapons have to have a completely different framework than a device.

Building that framework is in some ways more difficult than building the device. There are two challenges. One is size, and the other is ruggedization. A nuclear device is a precision instrument. It must begin by triggering an explosion so precise in energy and shape that it will trigger either a fission or fusion explosion. The tolerances are extraordinary. When a nuclear device is turned into a weapon, it must be miniaturized in order to fit on a rocket or an aircraft. A nuclear device has no such constraints. Miniaturization of anything that is only being tested in a static environment requires not only superb engineering, but extreme craftsmanship and quality assurance.

The same is true with ruggedization. Precision instruments require care. A nuclear weapon that is properly miniaturized must be able to go through high G-forces on a rocket, along with vibration, enter a vacuum where extreme temperature swings occur every few seconds, and then re-enter the atmosphere at high or extremely high temperatures, depending on distances and angles of re-entry.

It then has to detonate. The platforms that are being used, apparently missiles, must also go through the same precise engineering, or it can fail on launch or in delivery. Bear in mind that the United States, with the most advanced missile technology, still experiences periodic failures and early in its program in the 1950s, its missiles were constantly failing. In developing any technology, the early versions will fail, not because the developers are unsophisticated or sloppy, but because they haven’t had the experience to eliminate all of the shortfalls.

The million-dollar question is whether or not North Korea has developed a working nuclear bomb. While we like to believe that US intelligence has a clear understanding of North Korea’s weapons capability, those of us without classified clearance are forced to speculate. Yet, this does not preclude us from gaining a reasonable understanding of their program.

In March, Kim Jong Un was photographed in front of a miniaturized nuclear warhead (above). At the time, it was unclear whether the device was operational or simply intended as propaganda. However, two recent reports suggest that North Korea may indeed have succeeded in miniaturizing a nuclear warhead.

The first came from the annual Japanese Defense whitepaper, which stated, “It is conceivable that North Korea’s nuclear weapons program has already considerably advanced and it is possible that North Korea has already achieved the miniaturization of nuclear weapons and has acquired nuclear warheads…Since last year, when it forcibly implemented two nuclear tests and more than 20 ballistic missile launches, the security threats have entered a new stage.”

The second piece of evidence was courtesy of a leaked DoD report that claimed North Korea now possesses a miniaturized nuclear warhead capable of being mounted on a ballistic missile. Taken together, these reports suggest it is likely that North Korea has made progress in warhead miniaturization. However, significant challenges remain before it can reliably deliver a functional nuclear weapon.

We do not know whether North Korea has succeeded in ruggedizing their warhead and the precision of their detonating trigger. This calls into question the reliability of their system. North Korea’s nuclear tests can only occur underground; therefore, they cannot conduct a live fire exercise where they launch a missile with the device attached and test whether it can survive the flight and detonate at precisely the correct moment. Not only can North Korea not be assured of their weapon’s reliability without these tests, but the likelihood of success is low without this experience.

The third, and final, component needed for a deliverable nuclear weapon is a delivery system. In North Korea’s case, this means an operational missile capable of reaching its intended target.

North Korea has developed short and medium-range ballistic missiles that can be launched reliably and are capable of reaching South Korea and Japan. As a result, some pundits have argued that if North Korea has successfully built a working nuclear warhead, it effectively possesses all the components necessary for a nuclear strike. But the operative word is viable.

Technically, North Korea could deliver a nuclear bomb by attaching it to an aircraft and flying it over a target. But in practice, this delivery method is infeasible: any North Korean aircraft attempting to approach South Korean or Japanese airspace would be intercepted and destroyed long before reaching its target.

The same logic applies to North Korea’s ballistic missiles. While they can reach nearby targets, several limitations make them a questionable delivery system for nuclear weapons. Chief among them is the presence of robust missile defense systems. The United States has deployed the advanced Terminal High Altitude Area Defense (THAAD) system in the region, supplementing existing Japanese and South Korean defenses. To successfully strike either country, a North Korean missile would need to penetrate at least three layers of coordinated missile defense.

We also believe it is unlikely that North Korea would attempt to launch a short-range nuclear warhead at South Korea, even if it had the capability. The regime understands that the probability of successfully delivering such a warhead is low, while the consequences of failure (or even success) would be catastrophic and likely terminal for the regime.

The concept of “No First Use” (NFU) is a declared policy adopted by some nuclear powers, stating they will not use nuclear weapons unless first attacked with them.The US does not want to set a new precedent of using nuclear weapons in a non-retaliatory situation. However, if North Korea fires first, the US will be free to retaliate with nuclear strikes of their own. In fact, the US would be compelled to respond with a nuclear strike as they have pledged to defend South Korea and Japan with nuclear weapons in the event that they come under nuclear attack (The US has this agreement with 25 countries).

In such a scenario, the US would likely respond with tactical nuclear strikes, targeting hardened North Korean artillery and command sites, particularly those buried in mountainous terrain that are impervious to conventional bombing. From a military standpoint, a North Korean first strike could provide the US with the justification needed to decisively eliminate North Korea’s artillery terrorizing the South.

The news that North Korea had miniaturized a nuclear bomb capable of being married to a missile did not catch the US by surprise. This leads to an important question: why did Washington allow North Korea to cross such a critical threshold without taking military action? The most plausible answer is that US officials believed they could reliably neutralize the delivery system. In other words, the likelihood that a North Korean short-range missile, tipped with a nuclear warhead, could evade multiple layers of US and allied missile defenses and successfully detonate was judged to be acceptably low. This calculation allowed Washington to delay military intervention in favor of pursuing a diplomatic resolution.

More cynically, but perhaps more realistically, this delay also enabled President Obama to avoid becoming entangled in a war during the final months of his presidency, effectively passing the decision to act onto his successor. This context helps explain why President Obama reportedly told then President-elect Donald Trump that North Korea would be the most pressing issue he would face during his presidency.

So, what really constitutes Washington’s redline? Or to ask another way, what threshold is North Korea close to crossing in their nuclear program that has convinced Washington they remain only months away from obtaining a viable, deliverable nuclear weapon?

We believe the answer lies in North Korea’s progress toward developing an intercontinental ballistic missile (ICBM). If successful, this would give the regime a viable delivery system — completing the final step toward becoming a true nuclear power.

Current missile defense technology is highly effective at shooting down short and medium-range missiles, which have low trajectories; however, it has very limited ability to shoot down ICBMs due to their flight pattern (it is also ineffective against artillery). ICBM’s are designed to fly straight up and into orbit then re-enter the atmosphere in a near vertical trajectory over the target. In Japan’s recently released Defense white paper they specifically mention, “Missiles on a lofted trajectory are difficult to intercept.” It is not only the distance that ICBMs can travel but also their ability to bypass missile defense systems that has Washington so alarmed that North Korea is building these weapons.

Earlier this year the Trump administration confirmed that North Korea launched an intercontinental ballistic missile. The launch of a two-stage missile that, according to some experts, reached an altitude of 1,700 miles might indicate that the North Koreans have a platform for a nuclear weapon that could reach the United States. But that conclusion is premature.

North Korea is unlikely to have the guidance system required to target a US city. According to RAND Corp’s senior North Korea defense expert, “North Korea’s medium-range ballistic missile (No-dong) is believed to have more than 2km of CEP (Circular Error Probability) in its maximum range of 1,500km. If North Korea were to target the US with ICBMs, this error is expected to increase exponentially as the flight distance increases, and a missile would have to travel at least 6,000km to one city in western parts of the continental United States.”

However, North Korea does not need the capability to hit the United States before they will have a deterrent sufficient to prevent a US attack. If North Korea can develop a working ICBM, which can bypass missile defense systems and deliver a nuclear bomb to South Korea, Japan, or Guam, we believe it will be sufficient to deter the United States. In this case their guidance system limitations are less of an issue due to the shorter range and the fact that they will be targeting a large area, such as Seoul.

North Korea’s ICBM program has progressed rapidly but there are at least two more limitations that North Korea must solve before they can develop a working ICBM capable of delivering a nuclear warhead to South Korea or Japan.

North Korea must first develop a re-entry vehicle capable of protecting a delicate nuclear warhead from extreme temperatures upon re-entry into the earth’s atmosphere. Suspiciously, the Japanese white paper and the DoD report only mentioned that North Korea has developed a miniaturized nuclear warhead capable of fitting onto a missile but made no mention of the critical re-entry vehicle. However, North Korea has likely yet to develop this re-entry vehicle, as videos of their ICBM tests (including their latest test) have shown the missile burning up upon re-entry into the atmosphere.

Perhaps the greatest limitation to North Korea’s ability to deliver a nuclear-tipped ICBM concerns their ability to even launch their ICBM (Taepodong). Launching the Taepodong requires large surface infrastructure found in only two locations in North Korea, and long preparation times for launch make these missiles extremely vulnerable to US airstrikes. In other words, US forces can take out the missiles before North Korea ever launches them. It should be emphasized that North Korea’s current ICBM technology remains vulnerable to airstrikes, not missile defense systems, due to limitations in their current launch technology. However, North Korea is certainly working to overcome this hurdle. North Korea uses liquid-fueled rockets that take 30 minutes to fuel and must be moved around with a tanker truck in tow. If North Korea can develop a solid fuel rocket, it would significantly reduce this vulnerability. This could constitute North Korea’s final step before they can viably wage nuclear war. We can only speculate on a timetable, but we know they are growing close.

Reports estimate that North Korea could have a bomb capable of hitting the continental United States within a year. If this timeline is accurate, it implies North Korea will have the capability of hitting Tokyo even sooner. If the US is going to act, they will do so before Tokyo joins Seoul in becoming a hostage to Pyongyang.

US intelligence may feel like they have a good idea when North Korea will cross that redline but, as we saw in Iraq, intelligence is fallible and there is always the question of if you are missing something. The US administration also understands that the longer they wait for action the greater the repercussions of an intelligence failure. Therefore, in the coming weeks the Trump administration will be forced to make a final decision on North Korea’s nuclear program and inaction will constitute a decision in and of itself.

The final period between North Korea transitioning from a developing weapons program to a demonstrated system has always been the most likely time for military conflict. We are now in the midst of this window, as the next few months represents the last opportunity for the world to prevent North Korea from becoming a nuclear weapons state.

[1] Game theory is a set of models or concepts that attempt to capture the way participants think about strategic interactive situations. These are situations where one participant’s behavior depends on the way they perceive that the other participants in the situation will behave. In a static decision model, a participant will decide based on their perception of the cost and benefits of each option, but their actions do not impact the variables (ex. should I buy insurance). In contrast, game theory deals with dynamic situations in which participants must make a cost benefit analysis but to determine the costs and benefits they must predict how other actors will respond to their decision. In the deadly “game” between the United States and North Korea, each side must develop an understanding of the other side’s cost and benefits.

[2] There have certainly been more than six confrontations between the two countries since 1994 but there have only been six major diplomatic standoffs that occurred due to North Korea publicly testing and progressing their nuclear weapons program.