In 2017, North Korea conducted a very large, possibly thermonuclear, test explosion and proved it could build long-range ballistic missiles. Unfortunately, Kim Jong Un did not stop there. Since then his government has demonstrated an interest in submarine-launched ballistic missiles, hypersonic glide vehicles, solid-fuel rocket motors, and tactical nuclear weapons. Many observers worry that Kim intends to use this expanding and versatile nuclear arsenal not just to deter South Korea or its treaty ally, the United States, from attacking North Korea, but for coercion or “nuclear blackmail.”
This blackmail might take one of two possible forms. First, Pyongyang might use its nuclear weapons to keep the United States from intervening to help South Korea fight off a North Korean conventional military attack. North Korean nukes could negate the U.S. “nuclear umbrella” over South Korea by holding American cities at risk of incineration, or warn that the participation of U.S. conventional forces in the defense of South Korea would trigger nuclear retaliation against the United States.
Second, Pyongyang might threaten to use nuclear weapons against South Korea unless Seoul accommodates specific North Korean demands. These demands might include severing the South Korea-U.S. alliance and expelling U.S. forces based in South Korea, supplying North Korea with economic aid, or agreeing to some form of political unification of the Korean Peninsula that gives Pyongyang the upper hand over Seoul.
It would make sense for Pyongyang to threaten using nuclear weapons if an enemy appears to be winning a war aimed at overthrowing the regime. Facing such an existential threat, the regime would believe it had nothing to lose by playing its last and most fearsome card. Short of that scenario, however, attempting nuclear blackmail would not be an attractive option for the North Korean government.
In general, countries attempting to change the policies of other states by threatening the use of nuclear weapons have been unsuccessful. The target states don’t take the threat seriously, believing the threatening state is not prepared to suffer the political consequences of nuclear aggression.
Multiple official government statements indicate North Korea wants global recognition as a “responsible nuclear power.” This gives Pyongyang an incentive to demonstrate good international nuclear weapons citizenship. Nuclear coercion against South Korea during peacetime would immediately puncture that aspiration.
Initiating a conventional war against the South while using nuclear weapons as a shield would be a losing strategy for Pyongyang. It would be sheer folly to expect that South Korea would not fight back against North Korean aggression. Moreover, the South’s conventional forces are stronger than North Korea’s. Since 2010, South Korean governments have vowed to retaliate militarily against any lethal North Korean attacks. This has not changed as a result of Pyongyang acquiring of nuclear weapons.
If North Korea is the attacker, a threat by Pyongyang to initiate the escalation from the conventional level to the nuclear level is not credible because the United States is vastly superior to North Korea at the nuclear level. Threatening the first use of nuclear weapons against either the United States or South Korea would be an extremely risky move for Pyongyang because it might invite a devastating pre-emptive attack.
Pyongyang’s modus operandi is to intimidate adversaries by cultivating a reputation for unpredictability and belligerence. In practice, however, the North Korean government appears rather risk-averse. Pyongyang has backed down when confronted with a resolute response from its adversaries, as in the aftermath of the tree-trimming incident in 1976 and the tensions over South Korea’s border loudspeakers in 2015.
North Korea’s nuclear expansion does not necessarily indicate intent to practice nuclear blackmail.
North Koreans have reasons to believe a large and highly survivable nuclear arsenal is necessary to deter the United States from attacking their country. North Korea suffered extensive U.S. carpet bombing during the Korean War. Since then, Washington has maintained nuclear threats against North Korea in various ways, including basing tactical nuclear weapons in South Korea from 1958 to 1991, regularly flying aircraft capable of carrying nuclear weapons near North Korean territory, and making official statements such as then-U.S. President Donald Trump’s 2017 comment that he could “totally destroy North Korea.”
The United States has massive conventional and nuclear forces and is hard at work trying to improve its ability to shoot down incoming ballistic missiles. The South Korean government is seeking to build a capability to destroy North Korean ballistic missiles before they launch. With such formidable potential enemies, it is not unreasonable for Pyongyang to believe it needs a large and sophisticated nuclear weapons arsenal to convince Americans and South Koreans that it has a second strike capability, meaning it could absorb a nuclear attack and still be able to inflict unacceptable damage on the attacker.
While North Korea’s development of tactical nuclear weapons might suggest a plan to use nukes for warfighting or coercion rather than insurance, they could also be part of a fundamentally defensive strategy. Kim must account for the scenario in which his armies are losing a conventional war to superior South Korean-U.S. forces but he cannot nuke a major U.S. or South Korean city without bringing upon himself U.S. nuclear retaliation that would extinguish his regime and state. He might see the use of a tactical nuclear weapon against an enemy military target – rather than an enemy city – as a battlefield equalizer that would not necessarily draw massive U.S. retaliation, and might even frighten South Korean or U.S. forces into halting their advance.
Henceforth, the prominent feature of the North Korean nuclear weapons crisis will not be nuclear coercion, but rather mutual assured destruction (MAD).
As a result of the North Korean nuclear buildup, U.S. and South Korean anti-missile defenses are currently losing the battle of capabilities against North Korean missiles. This is no doubt what Kim intended. Rather than maintaining a minimal arsenal that enemy systems could possibly cancel out, he is building a larger and more robust arsenal that can overwhelm enemy defenses.
South Korea’s “kill chain” missile defense concept requires Seoul to know when and from where Pyongyang plans to launch a missile. Already difficult, this will become even harder as North Korea deploys missiles on submarines and transitions to solid fuel, which requires far less preparation time than liquid fuel.
The U.S. ground based interceptor (GBI) system has 44 missile-killing missiles based in Alaska and California, along the presumed path of enemy missiles incoming from Northeast Asia. This system would be hard pressed to shoot down even a small number of ordinary ballistic missiles. Kim may already have enough missiles to defeat the system, and he plans to mass produce nuclear bombs and their delivery vehicles. North Korea has apparently successfully tested a hypersonic glide vehicle, which can maneuver to avoid missile defenses such as the GBI system.
For its part, North Korea has no defense against incoming U.S. nuclear missiles.
Thus, for the foreseeable future, barring a dramatic new breakthrough in anti-missile defense technology, North Korea and its potential adversaries will feel safe only to the extent they believe their offensive capabilities are survivable enough to deter the other side from attacking. It will be a tense stability that reinforces the status quo rather than opening opportunities to redress it.