South Korean Defense Minister Estimates North Korea's Nuclear Warheads at 80 to 120, Trump Evaluates at 57

[Seoul = Takashi Tanaka] In the early hours of August 20, South Korea's Defense Minister An Kyung-bae stated in the National Assembly, "We generally estimate it to be between 80 and 120 warheads." He did not disclose specific numbers. The day before, on August 19, President Trump, during an inspection of the new White House helipad, told reporters, "Kim Jong-un has 57 very powerful nuclear weapons." It is rare, to the author's knowledge, for leaders and defense ministers of allied countries to publicly announce such differing numbers regarding the scale of the other country's nuclear capabilities overnight.

What the Numerical Discrepancy Indicates

The U.S. government and prominent think tanks have traditionally assessed North Korea's nuclear arsenal to be between 50 and 60 warheads, making Trump's estimate of 57 fall within that range. On the other hand, South Korea's estimate of 80 to 120 warheads is seen as an upward revision based on the expansion of nuclear material production capabilities at Yongbyon and military technology cooperation with Russia. Minister An stated, "We do not officially recognize North Korea as a nuclear-armed state," expressing a negative view on the abandonment of denuclearization.

Trump did not mention the timing of talks, but U.S. media reported that discussions are expected to coincide with the APEC summit in Shenzhen in November. Kim Yo-jong stated, "I have no knowledge of communications between the leaders," but added, "Good memories and feelings remain."

Implications for Japan

Japan's Ministry of Defense reportedly considers North Korea's number of nuclear warheads to be "several dozen." It is rare for the official assessments of Japan, the U.S., and South Korea to diverge to this extent. Moreover, this announcement comes right after the U.S.-South Korea joint exercise UFS26 was abruptly concluded about a week early at "the U.S. side's proposal." The timing is undeniably poor.

In the author's view, this discrepancy undermines the very calculations of extended deterrence. The required number of interceptors for BMD (Ballistic Missile Defense), the scale of standoff firepower, and the depth of information sharing among Japan, the U.S., and South Korea—all depend on estimates of "how many warheads the opponent possesses." If the numbers fluctuate with each change of administration, then the alliance's defense plans are built on sand.

Risks Posed by the Division in Assessment

If South Korea's estimate of 80 to 120 warheads is correct, there would be saturation even with the forward deployment of U.S. tactical nuclear weapons and the South Korean three-axis system. If Trump's estimate of 57 is correct, South Korea's overestimation could provoke an unnecessary arms race. At this point, it is impossible to definitively determine which is correct. However, the fact that leaders suddenly announce numbers and the defense minister contradicts them the next morning—this process itself is evidence that the information-sharing system within the alliance has become hollow.

The true test lies ahead of the "good relationship" that Trump prides himself on. If talks materialize and the nuclear issue is handled in the context of the personal relationship between the leaders, the mechanism for verifying the validity of the numbers will be lost from the alliance's side. Whether it is 57 or 80 to 120 warheads. Before deciding which number to believe, the question is who determines that number. Unless that question can be answered, Japan has no choice but to solidify the premises of its defense plans independently. That is not an easy path, either financially or institutionally.