한반도에서 중층적 안보구조와 고비용 신호: 북한의 4차 핵실험과 남한의 사드(THAAD) 배치 = The Security Structure and Costly Signaling at the Korean Peninsula: N. Korea`s 4<sup>th</sup> Nuclear Test and S. Korea`s THAAD Deployment

다국어 초록 (Multilingual Abstract)

The security structure of the Korean Peninsula is multi-layered. The upper layer is a place for the regional hegemonic competition between America and China, and confrontation in the lower layer is characterized as security dilemma between South and North Korea. Under such a security environment, North Korea`s 4<sup>th</sup> nuclear test is a signal by which it wants America to assure its national security. Against the North`s threat, South Korea decided the deployment of American THAAD in its territory. But the costly signals by North and South Korea cannot be delivered properly to major powers in the upper layer. The obstacles to disrupt two Koreas` intents of these signals are minimum trust threshold and the possibility of negotiation. South Korea and China put different standards for launching negotiation with North Korea. South Korea set too a high threshold as a precondition for negotiation and a low possibility of having effective negotiations with the North while Chine does a low level and a high possibility. South Korea`s strategic choice is the deployment of THAAD, which China perceives as a signal to threaten its security. North Korea`s 4^th nuclear test has generated China and South Korea to make unexpected payment for their security.