Overview

The 'One-Theatre' security concept is a strategic framework in international security policy that advocates for the integrated consideration of contiguous or related geographical regions as a single operational theatre. In the context of East Asia, this concept has gained prominence due to rising geopolitical tensions, particularly surrounding the maritime domains of the East China Sea, South China Sea, and the Korean Peninsula.

Historical Background

Efforts to treat interconnected regions as unified operational theatres have roots in both Western and Asian military doctrines. The approach emphasizes the seamless coordination of military, intelligence, and diplomatic actions across adjacent maritime and aerial spaces. This facilitates more effective responses to complex, transnational security challenges, such as territorial disputes, freedom of navigation operations, and assertive actions by regional powers like China.

Application in East Asia

The 'One-Theatre' concept in East Asia is largely driven by Japan and its allies, especially in response to China's expanding maritime presence. It promotes the integration of defense planning among like-minded nations including Japan, the Philippines, the United States, South Korea, and Australia. Collaboration under this model includes intelligence-sharing, operational synergy, and mutual reinforcement, particularly in naval and aerial defense. The approach was notably discussed at high-level meetings, as Japanese Defense Minister Gen Nakatani formally proposed the idea to U.S. and regional counterparts in early 2025.

Strategic Implications

By treating discrete but adjacent maritime spaces as one operational theatre, involved countries can:

• Enhance situational awareness across borders.
• Increase the speed and effectiveness of joint responses to security incidents.
• Create unified command structures for specific missions or contingencies.
• Share intelligence and resources more efficiently.

While proponents argue this model is necessary for countering multifaceted regional threats, critics caution it could escalate tensions by blurring traditional boundaries of sovereignty and operational jurisdiction.

Related Concepts

• Maritime Domain Awareness (MDA)
• Collective Security
• Quad (Quadrilateral Security Dialogue)
• Freedom of Navigation Operations (FONOPs)

See Also

• East China Sea Dispute
• South China Sea Arbitration
• Japan–Philippines Security Relations
• U.S.–Asia Security Alliances