File photo: A Japan Air Self-Defense Force F-15J fighter jet lands at the Royal Air Force Coningsby in the UK.
资料图：日本F-15J战斗机降落在英国科宁斯比空军基地。
Recently, Japan and the UK have increased the frequency of their defense interactions and expanded the scope of their cooperation. Analysts believe that the warming of Japan-UK defense ties is a chain reaction triggered by NATO's Indo-Pacificization strategy and the trend toward a more outward-looking Japan Self-Defense Force. However, due to multiple constraints, the cooperation between the two sides appears to be more about posturing than achieving substantive results.
近期，日本和英国防务互动频次增加，协作范围扩大。有分析认为，日英两国防务合作升温是“北约印太化”策略与日本自卫队外向化发展趋势引发的连锁反应。不过，受多重因素限制，双方合作呈现造势大于实质的特点。
Multiple Areas of Cooperation
展开多项合作
Recently, the Japan Air Self-Defense Force completed its first-ever intercontinental deployment operation, codenamed Atlantic Eagle, dispatching fighter jets to Europe. This mission was a key topic during talks between Japanese Defense Minister Gen Nakatani and UK Defense Minister John Healey held in Tokyo at the end of August. The two sides explicitly expressed their intention to further strengthen defense capability building and security cooperation. Before this, Japan and the UK had already launched maritime cooperation. In August, the Royal Navy's aircraft carrier HMS Prince of Wales carrier strike group made a port call at Yokosuka, Japan, and conducted joint exercises with the Japanese side. Subsequently, the Japan Maritime Self-Defense Force destroyer JS Akebono (DD-108) joined the British carrier strike group for deployment in the far seas. Regarding bilateral maritime cooperation, UK First Sea Lord Admiral Sir Gwyn Jenkins stated that naval interactions between the UK and Japan would become closer and more detailed, with plans to establish a reciprocal aircraft carrier visit mechanism. While defense collaboration continues to advance, cooperation between Japan and the UK in the defense industry is also deepening in parallel. In the space sector, Japanese and British companies have reached cooperation agreements to build a satellite constellation system primarily aimed at collecting surface intelligence. In the unmanned systems field, a British drone development company has been actively promoting small unmanned aerial vehicles to relevant departments of the Japan Self-Defense Forces. In the fighter jet domain, both countries have pledged to accelerate the development of their next-generation fighter program (GCAP). In the underwater equipment sector, the two sides plan to explore potential cooperation on underwater technologies within the framework of the AUKUS security alliance.
近日，日本航空自卫队完成代号“大西洋之鹰”的跨洲际部署行动首次向欧洲派驻战斗机。此次行动是日本防卫大臣中谷元与英国国防大臣希利8月底在东京举行会谈的重要内容，双方明确表示将进一步加强防务能力建设和安全合作。在此之前，日英海上协作已先行展开。8月，英国海军“威尔士亲王”号航母打击群停靠日本横须贺港，并与日方展开联合演习。随后，日本海上自卫队“曙”号导弹驱逐舰加入英国海军航母编队，进行远海部署。对于两国海上合作，英国第一海务大臣詹金斯表示，英日两国海上军事互动将“更趋紧密、更注重细节”，并计划建立航母互访机制。在防务协作持续推进的同时，日英两国在军工领域的合作也同步深化。航天领域，日本与英国相关公司达成合作，计划构建卫星星座系统，主要用于地表情报采集。无人装备领域，英国无人机研发企业向日本自卫队相关部门针对性推销小型无人机。战斗机研发领域，两国共同表示，将加快新一代战斗机项目（GCAP）研发进程。水下装备领域，双方将探索在“奥库斯”联盟框架下，开展水下技术等领域合作的可能性。
Each Side with its Own Calculations
双方各有所图
The growing military closeness between the UK and Japan essentially reflects a relationship of mutual convenience driven by their respective national interests.
英日两国在军事领域持续走近，本质上是双方基于自身利益的相互利用。
For the UK, strengthening ties with Japan allows it to play a more active role in Indo-Pacific affairs. As a key US ally in the region, Japan possesses a well-developed network of airports, ports, and logistical facilities that can help reduce the operational costs of the UK in expanding its military presence there.
对英国而言，其希望通过拉近与日本的关系，更多介入印太地区事务。日本作为美国在印太地区的重要盟友，拥有较完备的机场、港口及后勤设施，能够降低英国介入该地区的军事成本。
For Japan, closer cooperation with external partners serves as a means to gradually advance its goal of achieving the so-called national normalization. In recent years, Japan's growing tendency to break through the constraints of the pacifist constitution has met strong resistance from domestic peace advocates. To counter such opposition, Japan seeks to bring in extra-regional powers such as the UK to participate in Indo-Pacific affairs, thereby creating a so-called internationally mainstream narrative to legitimize its actions. At the same time, Japan aims to enhance its combat readiness and long-range power projection capabilities through joint tactical training. Some Japanese think tanks argue that cooperation with the UK could help Japan integrate into NATO's military cooperation framework and gradually reduce its overreliance on the US.
对日本而言，其希望借助外部力量，逐步实现“国家正常化”目标。近年来，日本不断突破“和平宪法”限制的趋势受到其国内和平力量反对。为此，日本意图通过引入英国等域外国家参与印太事务，为自身行动营造所谓“符合国际主流”的舆论氛围。同时，日本希望通过联合战术训练，提升自身作战能力与远海投送能力。有日本国内智库称，与英国合作可以为日本“融入北约军事合作框架、逐步降低对美国的单一依赖”积累条件。
Insufficient Cohesion in Bilateral Cooperation
合作黏性不足
The depth of defense cooperation between Japan and the UK remains limited due to inherent constraints arising from differences in geostrategic focus, disparities in capabilities, and divergent core interests.
两国深度合作受地缘战略不同、实力水平差距及核心利益各异等因素制约，合作黏性存在先天不足。
The UK's defense priorities are centered mainly on Europe and the Atlantic region, while Japan focuses on East Asia and the Western Pacific. Such strategic divergence leaves both sides with little incentive to commit substantial resources to areas outside their respective spheres of core interest. As a result, joint military exercises and related activities between the two countries tend to serve more as symbolic or episodic demonstrations rather than sustained, institutionalized cooperation.
英国的防务重心主要集中在欧洲及大西洋地区，日本则聚焦东亚及西太平洋地区。这种战略侧重差异，使双方缺乏向对方核心利益区域投入大量资源的足够动力。因此，两国开展的联合军演等行动往往呈现“阶段性造势多于常态化合作”的特点。
The composition of the UK's HMS Prince of Wales carrier strike group, augmented by warships from multiple allied navies, also underscores the current shortfall in the Royal Navy's independent force projection capability. The Japan Maritime Self-Defense Force, lacking an independent operational command system, finds it difficult to assume a leading role in high-end tactical coordination. The inherent capability gaps on both sides further exacerbate contradictions in bilateral cooperation. Due to differing regional security positions, the UK maintains only limited support for Japan's outward military development and remains reluctant to become deeply involved in Tokyo's territorial or strategic disputes with neighboring countries. For its part, Japan is also unable to provide substantial assistance to Britain's pursuit of global influence. In the short term, therefore, Japan–UK defense cooperation is likely to remain more demonstrative than substantive.
英国“威尔士亲王”号航母打击群由多国海军舰艇共同组成暴露出英国海军兵力不足的现状。日本海上自卫队则因缺乏独立作战指挥体系，难以在高端战术协同中承担主导角色。双方自身能力短板，将进一步加剧协作中的矛盾。受区域安全立场不同的影响，英国对日本自卫队外向化发展保持有限支持态度，不愿深度介入日本与周边国家的争端。日本对英国维系全球影响力的目标，也难以提供实质性支持。短期内，日英防务合作难以突破表面热络实质有限的局面。