Japan’s potential assistance in South Korea’s nuclear deterrence and defense

As North Korea emphasized its "second mission," the reunification of the two Koreas, with its nuclear weapons, South Korea has been mobilizing all potential resources to deter North Korea's attempt. Indeed, it rapidly improved its relations with Japan as well as strengthened the U.S. extended deterrence through the "Washington Declaration" in early 2023. The United States, South Korea, and Japan even initiated their trilateral summit meeting to discuss their combined deterrence posture against North Korea. This article evaluates South Korea's current nuclear preparedness, including preemptive/preventive strikes, missile defense, and civil defense, identifies weaknesses, and analyzes whether Japan can mitigate the weakness.