• The ballistic missile submarine USS Kentucky docked in Busan, South Korea this week.
  • The sub’s visit is part of a more visible display of U.S. nuclear weapons systems meant to deter North Korea.
  • North Korea says the sub’s arrival could meet the conditions under which it would use nuclear weapons, but a first strike by the North is not in the cards.

North Korea’s defense minister warned that a visit of a nuclear-armed missile submarine to South Korea could fulfill the conditions by which it could use nuclear weapons. The statement, although chilling, is not backed up by reality. North Korea’s nuclear leverage, consisting of about 30 nuclear weapons, is not useful when there is no crisis, and when no existential crisis to the country is imminent.

Bombers, Subs to Korea

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USS Kentucky, an Ohio-class ballistic missile submarine, is currently in Busan, South Korea as part of a deal hammered out a few months ago between Washington and Seoul. Under the deal, South Korea has put off developing its own nuclear weapons in return for closer coordination with the Pentagon on nuclear issues. According to South Korean President Yoon Suk Yeol, the agreement also includes the “deployment of U.S. strategic assets on the Korean Peninsula” that will be “be done regularly and continuously.”

The United States is fulfilling its end of the deal, sending more hardware to South Korea as a show of strength. In June, multiple B-52 Stratofortress bombers flew over South Korea, and photos seem to indicate at least one of the bombers was equipped to carry nuclear weapons. Not all B-52H bombers are capable of carrying nuclear weapons, and those that do feature small fins towards the rear fuselage that visually denote them as nuclear-capable.

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June also saw the missile submarine USS Michigan visiting Busan. Although it is an Ohio-class missile submarine, nuclear treaty obligations saw Michigan stripped of its nuclear-tipped Trident missiles and converted to carry cruise missiles. The 560-foot long, 18,000-ton nuclear-powered submarine can now carry up to 154 Tomahawk cruise missiles, including both land attack and anti-ship versions.

Rules and Warnings of a Nuclear Attack

us ballistic missile submarine uss kentucky visits south korea
South Korean television showing footage from a North Korean Hwasong-17 intercontinental ballistic missile launch, November 2022.
Getty Images

According to Yonhap News, North Korean Defense Minister Kang Sun-nam warned that the visit by the USS Kentucky “may fall under the conditions of the use of nuclear weapons specified in DPRK law on nuclear force policy.” Kang is in effect describing a pre-emptive strike on the United States, one designed to destroy American nuclear weapons before they could be used on his country.

Like all countries with nuclear weapons, North Korea has set rules on when it can use nuclear weapons. Although using nukes may seem like a “you’ll know it when you see it” kind of situation, in which the time to unleash them is glaringly obvious, rules allow leaders to focus their thinking and make decisions within a framework—particularly in times of stress and duress.

One of the situations in which North Korea would allow itself to use nukes is when their use is “imminent” by the other side. Defense Minister Kang is implying that the visit of a missile-armed submarine to South Korea could be viewed as one sign that a nuclear attack is inevitable.

First Strikes: Not For Everyone

north korea kim jong un waving to military members
This undated picture released from North Korea’s official Korean Central News Agency (KCNA) on September 16, 2017 shows North Korean leader Kim Jong-Un (R) inspecting a launching drill of the medium-and-long range strategic ballistic rocket Hwasong-12 at an undisclosed location.
Getty Images

A pre-emptive nuclear attack, or nuclear first strike, is designed to catch the enemy by surprise and destroy as much of his nuclear weapons and command and control assets as possible. The attack is supposed to be so thorough that the enemy has little to nothing to retaliate with, leaving it with surrender as the only option. The problem is that, if the enemy retaliates with even a handful of nukes, that could make the attack not worth it. It’s this uncertainty that has helped make a nuclear first strike a strictly theoretical exercise.

A pre-emptive attack by North Korea is not in the cards and probably never will be. As of 2022, North Korea is estimated to possess 20-30 nuclear weapons, and is likely busy expanding its arsenal. By contrast, the USS Kentucky, one of 14 U.S. submarines with nuclear weapons, is equipped with 20 ballistic missiles and a total of 90 nuclear warheads. Overall, the U.S. has 5,244 nuclear weapons, including 1,670 currently deployed on missile submarines, bombers, and at NATO air bases in Europe.

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North Korea has far too few nuclear weapons to execute a successful pre-emptive strike on the U.S. It is doubtful that even Russia could accomplish such an attack, as it would be unable to target submarines like the USS Kentucky.

The only scenario that is remotely viable is if North Korea executes a first strike against U.S. military bases in South Korea and Japan, with the reasoning that the American public would recoil at the losses and demand an end to the war. But the American public could just as easily demand massive retaliation, and the strike would also draw in South Korea and Japan as combatants.

The Takeaway

North Korea had to respond to an American nuclear armed submarine visiting South Korea, and it responded with bluster. That’s better than responding with weapons. There is no situation in which North Korea uses its nuclear weapons first and survives what comes next. For the foreseeable future, the country’s nuclear weapons are for self-defense only.

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Kyle Mizokami

Kyle Mizokami is a writer on defense and security issues and has been at Popular Mechanics since 2015. If it involves explosions or projectiles, he's generally in favor of it. Kyle’s articles have appeared at The Daily Beast, U.S. Naval Institute News, The Diplomat, Foreign Policy, Combat Aircraft Monthly, VICE News, and others. He lives in San Francisco.