Japan’s OSA: A Quiet Bet On Security Partnerships – Analysis

By Pratnashree Basu

Japan’s Official Security Assistance (OSA) framework is quickly becoming a key pillar of Tokyo’s evolving security diplomacy. Launched in April 2023, the OSA marks a deliberate departure from the development-only confines of the traditional Official Development Assistance (ODA) by allowing the provision of defence equipment and related security-enhancing transfers. OSA allocations, viewed through the lenses of strategy, geography, capability impact, and regional political economy, must be contextualised against a rapidly shifting architecture of security cooperation in the Indo-Pacific.

Underpinned by the revised National Security Strategy, the OSA institutionalises the grant of military-relevant equipment to strengthen the deterrence capacities of partner countries, with clearly stipulated constraints: assistance must not be directly associated with active conflict zones and is presented as supporting public order, including assisting monitoring and humanitarian functions rather than frontline combat operations.

In its FY 2026 budget, the Cabinet has proposed Yen 18.1 billion (US$116 million) for the OSA programme, more than double the amount allocated in 2025. While initial allocations were modest, Tokyo has incrementally increased OSA funding since its inception. If the Cabinet’s allocation is approved, this fiscal momentum would signal a sustained commitment to the policy shift within Japan’s strategic establishment, positioning OSA as a mechanism for long-term security cooperation.

It also signals Tokyo’s intent towards placing greater monetary and political weight behind security assistance, particularly in Southeast Asia, where surveillance radars, UAVs, and patrol craft have become the instruments of choice. In fact, in the three years since its inception, the OSA programme has already demonstrated diversification in instrument type and capability focus. In the Philippines, for instance, current OSA projects include funding for infrastructure such as boathouses and slipways that support maritime patrol capabilities — a clear expansion from equipment provision, such as patrol boats and radars, to logistics and facilities. At the same time, by focusing on assistance related to the provision of defensive assets, Tokyo is balancing domestic sensitivities around military aid while incrementally supporting the defence postures of recipient countries. Official documents emphasise non-lethal, capacity-building uses: surveillance, counter-terrorism, piracy control, and disaster relief, to underscore that OSA is not a militaristic tool. Yet the choice of equipment and the volume of transfers inevitably place Japan squarely within the Indo-Pacific’s security assistance competition, prompting an assessment vis-à-vis other existing security outreach mechanisms, particularly those of the United States and China.

In the broader Indo-Pacific security landscape, China’s security assistance — whether through infrastructure financing via the Belt and Road Initiative, military diplomacy, or weapons exports — has been both expansive and assertive. Beijing’s strategy, particularly in Southeast Asia, Africa, and the Pacific, combines financial incentives with the supply of defence equipment and training, frequently with fewer policy restrictions. As a result, a distinct engagement paradigm has emerged over the last decade, appealing to states seeking rapid capability acquisition with minimal normative constraints.

Japan’s OSA, in contrast, represents an approach predicated on transparency and non-coercion. Tokyo positions OSA as enabling partner countries to build their own defensive and surveillance capacities without influencing their sovereign choices. Unsurprisingly, China has criticised OSA as an attempt to counterbalance Beijing’s influence, warning that it may deepen bloc dynamics and heighten regional tensions — an illustration of how China’s abrasive regional diplomacy frames even relatively low-scale assistance programmes. Nonetheless, this juxtaposition is not merely rhetorical. The extension of OSA to Mongolia, Djibouti, and Pacific Island countries beyond immediate Southeast Asia reflects a calibrated effort to remain engaged in regions of growing strategic importance, ensuring that Japan is neither absent from nor marginal to evolving security conversations where Chinese engagement is already substantial. In this regard, OSA allocations also function as a geostrategic signal to domestic audiences and regional partners alike about Tokyo’s steady steps towards becoming a proactive security partner.

The long-standing security commitments of Washington towards the Indo-Pacific — although they are presently in jeopardy — must also be taken into account when assessing Tokyo’s security support. OSA is more limited in both scope and scale than US assistance, with Washington offering more sophisticated weapons and broader interoperability programmes under frameworks such as Foreign Military Financing(FMF) and large defence contracts. Hence, while US support includes comprehensive defence systems and integrated military aid, Tokyo’s focus remains on surveillance and domain awareness. Yet the two are not incongruent. Japan’s OSA complements US strategy by providing piecemeal capacity-building that fills gaps left by US prioritisation, particularly as US forces are globally committed, while offering partner nations a third option — a security cooperation alternative not directly tethered to American military assistance.

However, the OSA’s approach is not frictionless. Differing threat perceptions between Washington and Tokyo, domestic political constraints in Japan, and the often divergent strategic cultures of ASEAN member states complicate policy coordination — a reality now sharpened by renewed uncertainty in US politics. This has, in turn, made it clear to Tokyo that strategic dependence on Washington alone is no longer a viable hedge. These developments underscore the careful balance Japan must maintain in its regional security diplomacy.

Another important dimension is that recipient states are not passive actors. Countries such as Malaysia, the Philippines, and Indonesia — all OSA recipients — actively balance their security ties with Japan, the United States, and China according to their own strategic priorities. For partners wary of antagonising Beijing, Tokyo’s insistence on non-offensive uses of its security assistance lowers domestic political risk. In contrast to Chinese or American security offers, which are often perceived as more politically charged, this creates a distinct value proposition. The inclusion of Thailand and the identification of Cambodia, Vietnam, and Laos as potential next-round recipients will further widen Japan’s security footprint across continental Southeast Asia. By extension, OSA will become more deeply integrated into Japan’s broader geostrategic agenda of shaping security practices in strategically consequential spaces.

• About the author: Pratnashree Basu is an Associate Fellow at the Observer Research Foundation.
• Source: This article was published by the Observer Research Foundation.