Efforts by South Korea and the United States to strengthen their posture and capabilities in response to North Korea's accelerating nuclear force modernization are unavoidable. The concern, however, is that deterrence-only military measures undertaken in the absence of adequate efforts to manage the Korean Peninsula situation in a stable manner may heighten strategic instability on the peninsula. Deterrence is fundamentally a threat-based strategy, and the instability inherent in the nuclear age is prone to further deterioration through the parties' competition in deterrence capabilities. A side that fears a preemptive strike may opt for the delegation of nuclear launch authority and the maintenance of a high alert posture, which in turn can raise the risk of accidental nuclear war through miscalculation and mechanical malfunction. An additional adverse effect arises as North Korea's nuclear force modernization and South Korea's buildup of advanced conventional forces interact to trigger a ceaseless arms race. In short, the deterrence competition between the two Koreas may produce the twin harms of crisis instability and an arms race on the Korean Peninsula.

The problems of nuclear crisis stability and arms racing currently manifesting on the Korean Peninsula are issues that were already fiercely debated during the U.S.-Soviet Cold War. The two superpowers were continuously engaged in nuclear arms competition and were particularly preoccupied with early warning and prompt nuclear response postures driven by fear of a preemptive strike. The Launch on Warning (LoW) posture was devised to enable nuclear retaliation before it was too late, and pressure for the advance delegation of nuclear launch authority intensified. When decapitation strikes against the Kremlin leadership were raised as a possibility, the Soviet Union went so far as to establish an automated nuclear strike system known as the Dead Hand. As illustrated by instances of early warning radar malfunction, all of these factors were sources of instability that raised the risk of accidental nuclear war. Even setting aside the possibility of accidental nuclear launch, the problem was that once a crisis escalated beyond a certain threshold, the pressure to act first would lower the threshold for nuclear use. In practice, the United States and the Soviet Union experienced several dangerous moments in which they inadvertently approached the brink of nuclear war. A review of the history of Cold War nuclear strategy thus reveals historical lessons replete with implications for the Korean Peninsula, including debates over nuclear doctrine and the dangerous thresholds of inadvertent escalation. Examining the risks of inadvertent escalation raised during the Cold War era is therefore expected to provide important lessons for preventing the tragedy of nuclear war on the Korean Peninsula.