북한의 핵무기 선제 사용의 조건: 게임 모델을 통한 접근

Abstract

This study addresses the question of under what conditions North Korea would initiate a nuclear attack on South Korea. Recognizing that North Korea’s decision calculus is contingent upon U.S. extended deterrence, the study develops a game-theoretic model in which North Korea is unsure of the U.S. resolve to uphold its nuclear umbrella. The equilibrium analysis yields two outcomes and associated conditions for North Korean first use of nuclear weapons In the first equilibrium, North Korea’s enhanced second-strike capability deters U.S. retaliation: anticipated U.S. losses from North Korea’s retaliatory strike exceed Washington’s domestic and international audience costs, or the United States, anticipating such costs, explicitly abandons its nuclear umbrella ex ante. In the second equilibrium, North Korea’s decision to strike first relies on three interrelated factors: the probability of U.S. retaliation, North Korea’s expected gains from initiating a nuclear attack, and the expected costs from a U.S. retaliatory strike. A comparative statics analysis from the second equilibrium show that under an illustrative assumption of a 50 percent chance of U.S. retaliation, incentives for first use arise only if the expected gains exceed the expected costs of retaliation—an unlikely condition given the anticipated scale of U.S. nuclear retaliatory capabilities. Accordingly, the scope for North Korea’s nuclear first use appears highly limited, implying that North Korea’s deterrent threat for regime survival may be credible, but its threat of nuclear coercion is not.