Cossa, Ralph

Abstract
The three-way relationship among the US, Japan, and ROK today (a unified Korea at some point in the future) will have a profound impact on the broader East Asia geopolitical environment and will help define the nature of the US-Japan-China relationship and other regional triangles and broader multilateral configurations.
The security policies of all three are closely linked today through the common denominator of the US-ROK and US-Japan bilateral alliances. The Trilateral Coordination and Oversight Group has helped to institutionalize this three-way cooperation, at least in as dealing with North Korea. Close security cooperation among Tokyo, Washington, and Seoul has already paid rich dividends in pressuring North Korea both to keep its Agreed Framework commitments and stop testing missiles, as well as helping set the stage for direct North-South dialogue by demonstrating to Pyongyang that a divide-and-conquer strategy would not work.
Absent a clear and present threat, a formal, official trilateral security alliance is neither necessary nor advisable, however, either today or in a post-unification era. There is little strategic value in formalizing Japan-ROK or broader trilateral ties. It is the central theme of this article, however, that a “virtual alliance” is in the interest of long-term peace and stability. This can be achieved through the maintenance of a reinvigorated US-Japan alliance, the continuation of a solid US-Korea security relationship after unification, and the strengthening of bilateral security cooperation between Tokyo and Seoul.
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