North Korea's 600mm Autonomous Guided Rocket Reveals New Vulnerabilities in Japan's Air Defense Network

On the morning of January 27, the Japanese Ministry of Defense detected two short-range ballistic missiles, but in reality, there were four. This "detection failure" is not merely a technical issue. The test launch of the 600mm multiple launch rocket system equipped with North Korea's announced "autonomous precision guidance flight system" raises structural questions about the detection and tracking capabilities that Japan's missile defense network has relied upon.

New Generation Guidance System to Avoid GPS Jamming

According to North Korean state media, this test was conducted to verify the effectiveness of the "advanced large-caliber rocket system," which was inspected by General Secretary Kim Jong Un and his daughter Kim Ju Ae. Analysis by South Korean military experts suggests that this "autonomous precision guidance flight system" aims to counter GPS jamming and enhance precision strike capabilities.

This technological evolution cannot be overlooked by Japan. The Aegis system and PAC-3 operated by the Japan Maritime Self-Defense Force and the Japan Air Self-Defense Force perform interception calculations based on predictable ballistic trajectories. However, missiles with autonomous guidance capabilities can adjust their trajectories during flight, potentially deviating from the "parabolic" paths assumed by traditional interception algorithms.

What the Detection Discrepancy Implies

North Korea announced that four missiles were launched, but the South Korean Joint Chiefs of Staff and the Japanese Ministry of Defense could only detect two. The detected missiles reportedly flew 350 km and 340 km, landing on the island of Alsum in the Sea of Japan. There are two possibilities for this discrepancy.

One possibility is that the remaining two missiles flew at low altitudes or took irregular trajectories, thereby evading Japan's radar network. The other possibility is that the timing of the launches was extremely close, causing them to be processed as a single target on radar. In any case, if North Korea's announced flight distance of 358.5 km is accurate, this 600mm system not only brings the U.S. military base at Camp Humphreys in southern Korea within range but could also pose a threat to northern Kyushu across the Tsushima Strait.

Lack of Mention of "Extended Deterrence"

It is noteworthy that this test launch was conducted shortly after U.S. Deputy Secretary of Defense Elbridge Colby’s visit to South Korea. Colby emphasized "denial deterrence" in a speech in Seoul on January 26, but he did not provide a clear reaffirmation of "extended deterrence," which has traditionally been mentioned during visits by U.S. officials.

Extended deterrence refers to strategic assurances that include the U.S. nuclear umbrella. The absence of such mention may have been interpreted by North Korea as a sign of weakening U.S. defense commitments. In fact, after this test, Kim Jong Un praised the scientists and stated that he "hopes the enemy feels threatened." This is not merely a show of force but a political message testing the unity of the U.S.-South Korea alliance.

Japan's Dual Challenges

This situation presents Japan with dual challenges for its defense.

First, there is the urgency of a technical response. Against missiles with autonomous guidance capabilities, the speed of recalculating interception timing and the density of multi-layered defense could be a matter of life and death. North Korea's hypersonic missiles are said to have a flight time of less than three minutes, and if the 600mm multiple launch rocket is used in a saturation attack, the current missile defense system risks suffering severe losses in the initial stages.

Second, there is the need to reaffirm the reliability of the alliance. Colby's statements during his visit to South Korea suggest that the Trump administration emphasized "burden sharing" and sought to move away from the traditional "unilateral dependence." This also applies to Japan. The assumption that the U.S. nuclear umbrella will function automatically is no longer self-evident.

Conclusion: Information Sharing Speed Before Interception Capability

The Ministry of Defense has not disclosed details about the detection results, but my concern is whether information sharing among Japan, the U.S., and South Korea is functioning in real-time. The discrepancy where South Korea could only detect two missiles while North Korea claims four is not merely a matter of detection capability; it may indicate delays in the information integration process immediately after the launch.

The real challenge lies not in the technical advancement of missile defense systems but in the speed of decision-making among allied nations. In an era where North Korea possesses missiles that can reach Japan in three minutes, if the process from detection to interception decision takes ten minutes, then technical superiority becomes meaningless. The integration of command and control among Japan, the U.S., and South Korea should be the most urgent defense issue to be considered now.