Growing North Korean ICBM Threat Will Exacerbate Allied Concerns. In a recent military parade, Pyongyang trotted out the largest number of multiple-warhead ICBMs it has ever displayed at one time and unveiled a new solid-fueled ICBM. North Korea’s steadily expanding long-range missile arsenal risks overwhelming the limited number of ground-based interceptors defending the American homeland. This, in turn, will magnify escalating allied concerns that Washington, if faced with a credible nuclear threat from the regime, may not come to their defense against North Korean aggression.
North Korea’s New ICBMs
At a Feb. 8 parade celebrating the 75th anniversary of the founding of the Korean People’s Army, Pyongyang revealed at least 11 Hwasong-17 missiles, the world’s largest road-mobile ICBM. Experts assess that the missile, successfully flight tested in November 2022, can carry three to four nuclear warheads. This number of multiple-warhead missiles, along with North Korea’s other ICBMs, could inundate the 44 ground-based interceptors deployed in Alaska and California. U.S. officials have indicated they would fire multiple, perhaps up to four, interceptors at each incoming warhead.
North Korea also revealed a new containerized missile that is likely the prototype of a solid-fuel ICBM, a goal set by North Korean leader Kim Jong-un during a January 2021 speech. Pyongyang tested a static solid-fuel rocket engine last December 2022 and announced it had a thrust of 140 tons of force, greater than any U.S., Russian, or Chinese ICBM. Solid-fueled missiles reduce the time necessary for launch preparation, making them more difficult to detect and target.
North Korea’s ability to hold numerous American cities at risk of attack by hydrogen bombs has aggravated allies’ doubts about U.S. capability, resolve, and willingness to defend their countries. South Koreans have been increasingly vocal in questioning the strength and commitment of the U.S. extended deterrence guarantee, wondering whether the U.S. would be “willing to trade San Francisco for Seoul” or if it would instead abandon its ally.
Current and former South Korean officials privately express concern that the 2024 U.S. presidential election could lead to an isolationist administration that downgrades America’s alliance commitments, perceives the military relationship in transactional terms, and threatens to reduce or remove U.S. forces from the Korean Peninsula while unilaterally terminating combined military exercises and rotational deployment of U.S. strategic assets.
In January 2023, President Yoon Suk Yeol made a number of nuclear-related public statements that were at odds with his previous positions, U.S. policy, and ongoing bilateral discussions. Yoon appeared to deride U.S. extended deterrence as “the U.S. telling us not to worry because it will take care of everything. But now, it’s difficult to convince our people with just that.”
Yoon subsequently suggested that, if the North Korean threat worsened, South Korea might build its own nuclear weapons. The Administraton subsequently walked back Yoon’s comments, but that did not quell widespread media speculation of shifts in South Korean policy.
South Korean polls show high (over 70 percent) public support for an indigenous nuclear weapons program. Only 51 percent of Koreans polled in late 2022 believed the United States would actually implement extended deterrence to defend Seoul in case of hostilities on the Korean Peninsula.
Washington has taken steps to allay South Korean concerns about the strength of the U.S. extended deterrence guarantee. In 2022, the U.S. resumed, for the first time in four years, large-scale combined military exercises and rotational deployments of nuclear-capable strategic assets to the Korean Peninsula, including the USS Ronald Reagan aircraft carrier and B-52 bombers. Washington pledged to further enhance these deployments in a timely, coordinated, and routine manner.
Secretary of Defense Lloyd Austin and Minister of National Defense Lee Jong-sup pledged to further strengthen the alliance’s military capabilities and readiness through information sharing, training, exercises, and consultation, as well as joint planning and execution, to deter and respond to North Korea’s advancing nuclear and missile threats.
The U.S. and South Korea will conduct two table-top exercises simulating North Korean use of nuclear weapons and U.S. nuclear strategy and strategic asset responses to North Korean nuclear threat, imminent nuclear attack, and nuclear attack scenarios.
However, despite these and other measures, South Korean concerns remain. Washington must implement a comprehensive strategy of pragmatic nuclear policies, stronger nuclear coordination with its allies, robust military capabilities, and convincing communications of resolve to both opponents and allies.
What Must Happen Next
Washington should discern what additional measures would enhance reassurance, pressing for detailed recommendations from South Korea. To date, Seoul has not articulated specific measures that would allay its concerns.
The U.S. and South Korea should create a bilateral mechanism to coordinate on extended deterrence policies, including nuclear planning, options, contingencies, combined exercises, and deployment of U.S. strategic assets. Procedures should be delineated for including South Korea in crisis decision-making related to potential use of U.S. nuclear weapons.
While the U.S. could designate and empower an existing bilateral group as a nuclear consultative group, it seems that South Korea would perceive anything less than creating a new body with the Nuclear Planning Group moniker — commensurate with the existing NATO entity — to be insufficient.
The divergence between the U.S. and South Korea on extended deterrence mars what had been a near total alignment of policies following Yoon Suk Yeol’s inauguration. U.S. officials and Korea watchers in Washington had welcomed the change in South Korean administrations since Yoon brought pragmatic thinking on foreign and security policies.
The nuclear issue requires deft management by both sides. The U.S. must lean forward in trust-building efforts to assuage South Korean concerns. South Korea, in return, needs to manage public expectations as to what is possible. If North Korea continues its provocative actions, President Yoon will face greater pressure to do more.
If not handled well by both sides, the nuclear dispute risks causing tension in the alliance at a time when the two countries, along with other allies and partners in the Indo-Pacific region, need to be working closely together to address the growing North Korean and Chinese threats.
Author Expertise and World-Class Experience
Now a 19FortyFive Contributing Editor, Bruce Klingner is a senior research fellow specializing in Korean and Japanese affairs at The Heritage Foundation’s Asian Studies Center. From 1996 to 2001, Klingner was CIA’s deputy division chief for Korea, responsible for analyzing political, military, economic, and leadership issues for the president of the United States and other senior U.S. policymakers. In 1993-1994, he was the chief of the CIA’s Korea branch, which analyzed military developments during a nuclear crisis with North Korea.