Interoperability

Interoperability is the ability of different military forces, systems, and equipment to work together effectively, to communicate, coordinate, and combine their efforts as if they were parts of one force. It sounds like a technical nicety and is in fact a make-or-break factor in modern warfare, especially coalition warfare, because forces that cannot work together, whose radios cannot talk to each other, whose data will not share, whose ammunition does not fit each other's weapons, whose procedures clash, are far less than the sum of their parts, hobbled by the friction of incompatibility even when individually capable. The failures of interoperability are quiet but crippling: the allied units that cannot coordinate because their communications are incompatible, the coalition that cannot share targeting because its systems do not connect, the force that cannot resupply an ally because the ammunition does not match, all of which turn a combined force that should be powerful into a collection of forces that cannot fully combine.

Why interoperability matters so much

Interoperability matters because modern warfare is increasingly combined, fought by coalitions of nations and by the integrated efforts of different services and systems, and the effectiveness of these combined efforts depends on the pieces being able to work together. A coalition of allied nations fighting together, as in most modern military operations, needs its national forces to interoperate, to communicate across national contingents, to share information and coordinate action, to support each other logistically, and where interoperability is lacking, the coalition is weakened, unable to combine its forces effectively, its national pieces operating in partial isolation rather than as a coordinated whole. The same applies within a single nation's military, where the different services, army, navy, air force, and their various systems must interoperate to conduct the joint operations that modern warfare requires, and where a lack of interoperability between services or systems undermines the joint effort. Interoperability spans many dimensions: technical interoperability, the compatibility of communications, data systems, and equipment that lets them connect and share; operational interoperability, the compatibility of procedures, doctrine, and practices that lets forces coordinate their actions; and even the human dimension of shared understanding and trained coordination that lets forces work together smoothly. Achieving interoperability across all these dimensions, among the many forces, services, and systems that must combine in modern operations, is a genuine challenge, since the forces and systems were often developed separately, by different nations and services, with different standards and designs, so making them interoperate requires deliberate effort to establish common standards, compatible systems, and coordinated procedures. This is why interoperability is a major focus of alliances and militaries, pursued through common standards, joint exercises, shared systems, and the deliberate design of equipment and procedures to work together, since the combined effectiveness that interoperability enables is essential to how modern militaries fight.

NATO exists in large part as an interoperability enterprise, and its real value in a coalition often lies in the decades of interoperability work it has banked, the common standards, shared procedures, and habits of working together that let its many national forces combine effectively. NATO's standardization agreements, the STANAGs that establish common standards for everything from ammunition to communications to procedures, are the machinery of interoperability, ensuring that the alliance's diverse national forces can work together, that a weapon from one nation can use ammunition from another, that communications can connect across national contingents, that procedures align, so that when the alliance fights as a coalition, its pieces can combine rather than clashing. This interoperability, built up over decades of common standards, joint exercises, and shared experience, is a large part of what makes NATO militarily valuable, since it means the alliance's forces can actually combine their efforts effectively, a capability that a coalition assembled without such preparation would lack, as the friction of incompatibility would hobble it. The contrast is visible in efforts to support forces that were not built to Western interoperability standards, as when supporting Ukraine, whose Soviet-era equipment and the diverse array of donated Western systems, each with its own ammunition, communications, and support requirements, created enormous interoperability challenges, a logistical and operational complexity that Ukraine had to manage under wartime pressure, illustrating the cost of the interoperability that established alliances have and ad hoc coalitions lack.

Interoperability as a driver of standards and procurement

The importance of interoperability drives much of the standardization in military equipment and procedures, since achieving interoperability requires common standards that many forces and systems adhere to, making standardization a central concern of alliances and a significant factor in what militaries buy. The premium on interoperability pushes toward common standards, NATO's STANAGs and similar frameworks, that establish the compatibility, in ammunition, communications, data, procedures, that lets forces work together, and adherence to these standards becomes a requirement for equipment and forces that must interoperate, shaping procurement toward systems that meet the common standards and can connect with the broader force. This is why standardization compliance appears as a hard requirement in defense contracts, why equipment is designed to meet common standards even at some cost to national preference, and why the ability of a system to interoperate with the broader force is a significant factor in its value, since a superior but incompatible system that cannot work with the coalition may be less useful than a compatible one that can. The pursuit of interoperability also drives the effort to connect systems that were not originally compatible, the work of translating between different data links, communications, and systems so that forces and services fielded with different standards can still interoperate, a significant technical challenge and a growing area of effort as militaries seek to connect their many diverse systems into interoperable wholes, the ambition behind efforts to link any sensor to any shooter across services and nations. Interoperability, in short, is both a fundamental requirement of modern combined warfare, essential to the combined effectiveness of coalitions and joint forces, and a major driver of standardization and system design, shaping what militaries buy and how they build their forces, since the ability to work together, to combine forces and systems effectively, is so central to how modern militaries fight that ensuring it, through common standards, compatible systems, and coordinated procedures, is a continuous and significant priority.

Why don't all militaries just use the same equipment to ensure interoperability?

Because nations have their own defense industries, requirements, budgets, and preferences that lead them to field different equipment, so complete standardization on the same equipment is neither achievable nor desirable, and interoperability must instead be pursued through common standards that let different equipment work together. Nations maintain their own defense industries for economic and strategic reasons, wanting the jobs, technology, and self-sufficiency that come from producing their own equipment, and they have different requirements, budgets, and preferences that lead them to different choices, so expecting all militaries to field identical equipment is unrealistic, since it would require nations to abandon their defense industries and their own judgments about what they need, which they will not do. Instead, interoperability is pursued through common standards that establish compatibility without requiring identical equipment, so that different nations' equipment, though not the same, can still work together, using compatible ammunition calibers, communications standards, data formats, and procedures that let diverse systems interoperate, which is the approach NATO takes through its standardization agreements. This allows nations to maintain their own equipment and industries while still achieving the interoperability that lets their forces combine, a compromise between the impossibility and undesirability of complete standardization on identical equipment and the necessity of interoperability for combined operations. The result is that militaries field diverse equipment but adhere to common standards that ensure the diverse equipment can work together, so a coalition's forces, though equipped differently, can still communicate, coordinate, and support each other because their different systems meet the common standards that enable interoperability, achieving the combined effectiveness that interoperability provides without the unrealistic requirement of identical equipment, which is why the pursuit of interoperability focuses on common standards rather than common equipment, enabling forces that field different systems to nonetheless work together effectively.