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North Korea’s Tactical Nuclear Threshold Is Frighteningly Low

Pyongyang imagines it could win a limited conflict.

By , a senior fellow and the director of the Defense Posture Project at the Federation of American Scientists, and , a vice president of the Sejong Institute and former deputy minister for planning and coordination at the South Korean Ministry of National Defense.
A TV broadcasts footage of a North Korean missile test.
A TV broadcasts footage of a North Korean missile test.
A station employee cleans near a television showing a news broadcast with file footage of a North Korean missile test at a railway station in Seoul on Oct. 13. Anthony Wallace/AFP via Getty Images

This year, the threat from North Korea’s nuclear arsenal entered an alarming new phase. By mid-November, the regime had fired 63 ballistic missiles, more than double its previous annual record. The year’s tests included a record eight intercontinental ballistic missile (ICBM) launches, and U.S. and South Korean officials warn that the regime has completed preparations for a seventh nuclear test that waits on North Korean leader Kim Jong Un’s order.

However, 2022’s most alarming development is not about what North Korea could use to deliver a nuclear warhead, but when and why it plans to do it. In recent months, North Korean leaders have articulated a dangerous new doctrine for its expanding tactical nuclear arsenal. Unlike its strategic intercontinental missiles, which are probably a last resort to prevent regime change, the Kim family said its tactical weapons could be used at the outset of conflict to fight and win a limited war on the Korean Peninsula.

In 2021, Kim declared that the regime had undertaken a successful program to “miniaturize, lighten and standardize nuclear weapons and to make them tactical ones” and that North Korea would continue to “make nuclear weapons smaller and lighter for more tactical uses.” A return to nuclear tests could see tests of these new smaller warhead designs.

This year, the threat from North Korea’s nuclear arsenal entered an alarming new phase. By mid-November, the regime had fired 63 ballistic missiles, more than double its previous annual record. The year’s tests included a record eight intercontinental ballistic missile (ICBM) launches, and U.S. and South Korean officials warn that the regime has completed preparations for a seventh nuclear test that waits on North Korean leader Kim Jong Un’s order.

However, 2022’s most alarming development is not about what North Korea could use to deliver a nuclear warhead, but when and why it plans to do it. In recent months, North Korean leaders have articulated a dangerous new doctrine for its expanding tactical nuclear arsenal. Unlike its strategic intercontinental missiles, which are probably a last resort to prevent regime change, the Kim family said its tactical weapons could be used at the outset of conflict to fight and win a limited war on the Korean Peninsula.

In 2021, Kim declared that the regime had undertaken a successful program to “miniaturize, lighten and standardize nuclear weapons and to make them tactical ones” and that North Korea would continue to “make nuclear weapons smaller and lighter for more tactical uses.” A return to nuclear tests could see tests of these new smaller warhead designs.

Why might North Korea use a nuclear weapon? Most experts fall into two camps. The first theory warns that the regime could use nuclear weapons to retaliate against the U.S. homeland if it believed it was facing an existential attack, either from an allied invasion or an attack on Kim. The second theory is that North Korea might issue nuclear threats as part of an attack to forcibly reunify the peninsula, trying to blackmail South Korea into surrendering. In either case, the United States and South Korea would move to destroy North Korea’s nuclear forces and leadership before they can be launched and end the regime.

In recent months, North Korea has signaled that it is pursuing a third doctrine. In April, Kim said his nuclear forces will “never be confined to the single mission of war deterrent.” His sister and possible successor wrote, “[A]t the outset of war, completely dampen the enemy’s war spirits, prevent protracted hostilities and preserve one’s own military muscle.”

In other words, Pyongyang now envisions its nuclear weapons as useful not only for retaliation against an attack but for winning a limited conflict. This concept doesn’t require North Korea or its allies to launch a deliberate all-out attack, but it could guide the regime’s plans for any conflict, including wars that start by accident or that escalate from small crises. In short, the new doctrine might lead to nuclear use in a much wider set of circumstances—and much earlier in conflict.

Their mission is to prevent Washington and Seoul from bringing their superior forces to bear. The regime mistakenly hopes that early nuclear strikes could protect its inferior conventional forces and its leadership, allowing it to win a war it would otherwise lose. The targets could include strikes on stealth aircraft before they can leave the ground; units before they can be mobilized; and, as Kim said in October, strikes on his “enemies’ main military command facilities” and its main ports. It is a strategy that says nuclear weapons are not only for preventing war but also for waging one.

His sister’s comments also imply that the regime could try to win a hopeless conflict by coercing one or both of its allies to back down rather than risk a wider nuclear exchange. This mission is founded on several delusions: that North Korean nuclear use would help the regime control a conflict, that it would weaken rather than strengthen the alliance’s resolve, and that U.S. and South Korean defense chiefs would not follow through with their promise that “any nuclear attack” would result in the “end of [the] Kim Jong Un regime.” In other words, North Korea believes that nuclear use might end a conflict on its terms rather than end the regime.

The idea that a tactical nuclear weapon could help a country control escalation in a crisis is not new. At different times, Russia, France, Pakistan, and the United States have all relied on this dangerous theory when they believed that their conventional forces were too weak to deter a conflict. Why has Pyongyang adopted this logic now? It may be that North Korea has reached the point where it is capable of producing sufficiently miniaturized warheads and sophisticated ballistic missiles to deliver them. In countries building new nuclear arsenals, strategists often follow engineers.

The regime characterizes its new doctrine as part of its deterrence posture. It says North Korea can only deter an allied attack if it can win the conflict, and the only way it can win one might be early nuclear use. But Washington and Seoul will worry that the doctrine, with its emphasis on coercion and war termination, is designed to help Pyongyang win conflicts that it starts.

To deter North Korea from using its tactical nuclear arsenal, Washington and Seoul will have to adapt their posture and plans. The alliance cannot trust that existing concepts or the U.S. strategic arsenal can manage the escalation risks posed by Pyongyang’s new doctrine. The most important capabilities are the conventional forces that defend South Korea from attack and the political cohesion that signals that the regime cannot divide the alliance. Although the alliance will maintain its nuclear deterrent, only its conventional forces can deny North Korea from seizing its objectives in a conflict and respond to tactical nuclear use without legitimating the regime’s attack. The more Washington and Seoul emphasize preemptive attacks or attacks on the regime’s leadership, the more pressure the regime will feel to delegate authority to use tactical nuclear weapons to field commanders, which would further raise the risk of a nuclear accident or miscalculation.

These dangerous developments should also shape how allies approach diplomacy with North Korea. Although most American proposals have started with intercontinental missiles, allies should first focus on eliminating North Korea’s tactical weapons. Tactical nuclear weapons are not essential to the regime’s survival. The new doctrine is delusional. An arms control approach that allows the regime a sense of security in exchange for its tactical nuclear weapons stands a chance of succeeding and improving the security of both allies.

Washington and Seoul cannot afford to trust that their existing posture will deter North Korea’s new nuclear doctrine. As alarming as North Korea’s ICBMs are, its tactical nuclear weapons are now tasked with not only retaliation but a variety of missions to level the balance of power on the peninsula, which has been tipping against Pyongyang for decades. For these reasons, they are the likeliest of any nuclear weapons in the world to be used in war.

Adam Mount is a senior fellow and the director of the Defense Posture Project at the Federation of American Scientists. He holds a Ph.D. in government from Georgetown University. Twitter: @ajmount

Jungsup Kim is a vice president of the Sejong Institute and former deputy minister for planning and coordination at the South Korean Ministry of National Defense.

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