Originally published by Pacific Forum, the article is republished with permission.
What happens when North Korea demonstrably acquires an operational, reliable capability to strike the US mainland with a nuclear weapon?
For two decades, this question has lingered at the margins of policy debates. Today, North Korea is steadily approaching that threshold. Meanwhile the United States and South Korea remain constrained by an outdated framework, unable to move diplomatic engagement and military readiness beyond obsolete strategic assumptions.
The question sits at the center of a widening strategic gap between Pyongyang, Washington, and Seoul – one growing more dangerous as each side advances along increasingly incompatible trajectories.
Trump and Lee must align their policies with the new reality: the central challenge is no longer to prevent North Korea from reaching this threshold – it may already be too late for that – but to manage its consequences.
An irreversible shift
Following the collapse of talks with Trump and Moon, Kim Jong Un appears to have fundamentally redefined North Korea’s foreign policy and strategic goals.
Abandoning a decades-long approach established by his grandfather, Kim has chosen to base his country’s future not on normalization with the United States but on carving out a space for North Korea within an emerging multipolar world order.
Under this new strategic framework, a normalization-through-denuclearization deal with Washington loses relevance, while consolidation and advancement of its nuclear weapons program emerges as the primary strategic imperative.
Kim confirmed as much in his September 2025 statement that “the concept of ‘denuclearization’ has already lost its meaning. We have become a nuclear state.” Kim has repeatedly made clear that that diplomatic engagement with the United States is conditional on Washington abandoning its insistence on denuclearization.
At the Ninth Congress of the Worker’s Party of Korea in February 2026, where he outlined the regime’s new plan for the next five years, Kim Jong Un announced that North Korea would “strengthen the national nuclear force on an annual basis,” and “concentrate on increasing the number of nuclear weapons and expanding the means and space for nuclear operation.” To that end, he stated that the regime would “continuously conduct tests and drills” to ensure the effectiveness of its nuclear deterrent.
A widening strategic gap
Despite North Korea advancing its capabilities, Washington and Seoul still officially adhere to a denuclearization-first policy. They hesitate to shift toward arms control talks that could be interpreted as a tacit recognition of Pyongyang’s nuclear power status. In February 2026, US Secretary of States Marco Rubio and North Korean Foreign Affairs Minister Cho Hyun reaffirmed this objective in a joint statement.
As a result, the strategic and narrative gap between the two sides has widened farther, rendering US and South Korean re-engagement efforts based on the defunct frameworks of Singapore and Hanoi increasingly ineffective. One side remains anchored to long-dead denuclearization talks, while the other has transitioned to a new strategic mindset as an established nuclear power, working to expand its nuclear leverage and coercive capacity.
The growing strategic gap is partly because, despite North Korea’s 2017 hydrogen bomb test shifting threat perceptions in Washington, policy debates remain anchored in the assumption that Pyongyang does not yet pose a direct nuclear threat to the US mainland.
Questions persist about North Korea’s ability to effectively integrate a nuclear warhead with an ICBM capable of withstanding the rigorous conditions of launch, flight, and atmospheric reentry. Despite evident progress, US officials have noted that a full demonstration of this capability has yet to occur.
Admiral Samuel Paparo, commander of United States Indo-Pacific Command, stated in November 2024 that North Korea had not yet demonstrated the ability to deliver a nuclear warhead to the US mainland via ICBM. This assessment aligns with earlier remarks by Jake Sullivan, who back in 2022 had also highlighted uncertainties about Pyongyang’s capability to successfully pair, launch, and accurately deliver a nuclear-armed missile.
However, Kim’s statements during the Party Congress suggest North Korea’s acquisition of that capability is a matter of time rather than a mere possibility – and that moment may be closer than policymakers in Washington assume.
The approaching threshold
According to South Korean President Lee Jae Myung, only one critical step – mastery of atmospheric re-entry technology – may remain.
The North already possesses dozens of short- and medium-range missiles capable of striking South Korea and Japan, and estimates suggest it has sufficient fissile material for 50 to 100 nuclear weapons. Lee noted that Pyongyang likely already possesses enough nuclear weapons for regime survival, continues to produce fissile material and could add 15–20 warheads annually if current trends persist.
Although North Korea has not tested a nuclear warhead on a live missile, it has tested both components separately with growing reliability. Its ICBM launches have so far relied on lofted trajectories – shooting them very high into space to avoid international incidents – meaning it has not yet fully demonstrated real-world operational capability, especially in terms of range and re-entry. Pyongyang hasn’t proven the missile can survive the extreme heat of re-entering the atmosphere at full speed or hit a specific target far away.
Still, its stated intention to continue testing points to a clear effort to close that gap and move toward a credible nuclear deterrent against the United States, including through more advanced delivery systems such as submarine-launched missiles. To that end, there might also be further nuclear testing. While the 2017 test demonstrated thermonuclear capability, questions remain about full weaponization and integration with an operational ICBM. A new nuclear test would likely signal that North Korea is closing these remaining gaps.
As North Korea nears the ability to strike the United States with a nuclear-armed intercontinental ballistic missile, critical questions remain unresolved:
- What would signal a credible North Korean nuclear deterrent?
- How would the United States respond?
- What reactions would follow from Seoul, Tokyo, Beijing, and Pyongyang itself?
With diplomatic frameworks still fixated on denuclearization, discussions of arms control and risk reduction remain marginal – leaving these strategic issues largely unaddressed.
Strategic scenarios
North Korea appears determined to develop a nuclear deterrent capable of threatening the US mainland, thus securing regime survival and deterring American intervention, convinced that once it crosses that threshold, the strategic environment on the Korean Peninsula may change in its favor.
Yet Kim’s strategy may prove dangerously misguided. The United States has so far refrained from military action largely because of the unacceptable human cost of war on the Korean Peninsula and in the region. Any preemptive strike would carry significant risks, potentially prompting North Korea to retaliate against Seoul or Tokyo. It might draw China, which shares a border with North Korea, into the conflict – along with, perhaps, Russia.
This calculus could change significantly in the event of a direct threat to the US mainland. Already in 2022 Curtis Scaparrotti, former commander of US Forces Korea and the Combined Forces Command, noted that the prospect of a preemptive strike had gained traction amid North Korea’s ongoing missile tests and nuclear arsenal expansion.
Should the perceived threat in Washington shift from abstract to imminent, it could prompt consideration of a preemptive strike – the very scenario Pyongyang aims to avoid.
On the other hand, if nothing happens and North Korea crosses this threshold without a clear US response or fundamental policy shift, the credibility of American extended deterrence – already strained in the aftermath of the Russia-Ukraine war – could be further called into question.
First, regional allies may doubt whether Washington would risk its own cities to defend Seoul or Tokyo, potentially prompting new debates about indigenous nuclear capabilities.
Second, North Korea’s strategic calculus could shift: With a functioning deterrent against the United States, Pyongyang may feel emboldened to adopt a more aggressive posture toward South Korea, assuming Washington would hesitate to intervene directly.
The perils of strategic ambiguity
The main risk, however, lies in the strategic gap between the two sides, producing reluctance in Washington and Seoul to recognize a nuclear North Korea and to develop plans for managing the resulting challenges. If Pyongyang quietly crosses this threshold and catches its adversaries unprepared, it could trigger uncoordinated, delayed, and reactive responses.
Too many questions remain about a scenario in which Pyongyang can strike the US mainland – even disagreement over whether it already can. President Trump’s first step must be to end strategic ambiguity and achieve alignment within the US – across the military, policymakers, and the expert community – to establish a clear, shared understanding of how the United States would respond if this scenario were to unfold.
A second priority is to institutionalize regional arms control dialogue and crisis-management mechanisms – among allies and adversaries alike – reducing the likelihood of miscalculation or accidental war. Without established protocols for coordination with South Korea and Japan, and for communication with China and Russia – and in the absence of clear red lines or crisis-management mechanisms – uncertainty, misperception, and time pressure could drive less-than-rational decisions and misaligned responses, triggering escalation dynamics that risk spiraling into uncontrolled escalation or even accidental war.
Shifting Kim’s trajectory
There remains a small window for prevention. Kim Jong Un has left the door open for dialogue, but it may not stay open for long.
If North Korea’s growing hostility toward both the United States and South Korea is recognized as the central risk factor, Trump may still have an opportunity to alter this adversarial trajectory. Reopening diplomatic channels, establishing shared rules of deterrence, and potentially securing a new ICBM test moratorium – with the aim of encouraging Pyongyang to accept a regional, more manageable deterrent – remain possible developments.
However, if Washington continues to insist on denuclearization, diplomatic engagement will stall, and the opportunity to prevent, rather than manage, strategic escalation could close.
The current approach – anchored in strategic ambiguity, an increasingly obsolete objective, and unsupported by active diplomacy – risks leaving the United States and its allies unprepared for the rapidly emerging strategic reality. Without a more grounded and cooperative rethinking of strategic and diplomatic frameworks in Northeast Asia, the next phase of the North Korean nuclear crisis may be defined not by gradual escalation, but by sudden and potentially irreversible miscalculation.
Marialaura De Angelis (marialaura@pacforum.org) is a resident James A. Kelly Korea Fellow at Pacific Forum and an affiliated researcher at the East-West Center in Hawai‘i. She also serves as a senior advisor to the NGO Track2Asia in Brussels.