MOSA cadre to guide weapons programs
NewsSeptember 24, 2026
NATIONAL HARBOR, Maryland. The Department of War has formed a team of modular open systems approach (MOSA) experts to help weapons programs apply open architectures and meet new department expectations, a senior acquisition official said at the 2026 MOSA Industry and Government Summit.
James Ruocco, performing the duties of Assistant Secretary of War for Acquisition, said the MOSA cadre will work directly with program teams and show them how to implement modularity. The department has also issued a memorandum describing its minimum expectations for MOSA implementation, he said.
The cadre will follow models already used for software and intellectual-property issues. Ruocco said the effort could grow through a “train the trainer” approach, with experts working alongside program personnel instead of relying mainly on classroom instruction.
Senior leaders will also use MOSA measures to evaluate program health, Ruocco said. Portfolio acquisition executives and program managers will receive more authority, but they will also be held responsible for delivering open and modular systems.
“MOSA is not achieved because the program uses the word ‘open,’” Ruocco said. “It’s achieved when the standard interfaces are implemented, tested, reused, and applied across programs.”
Programs must include modularity in their requirements, architectures, contracting strategies, budgets, interface standards, and data-rights plans from the beginning, he said. Treating MOSA as a late integration problem can leave programs tied to closed systems that are difficult to upgrade or sustain.
Ruocco said proprietary implementations of open standards are not truly open. Intellectual property can remain inside a component or subsystem, he said, while the interfaces needed to connect and replace that component should remain open.
The department wants modular architectures to increase competition, reduce dependence on individual suppliers, and let programs insert new technology faster. Common interfaces could also give small businesses and nontraditional suppliers a path to provide components for several platforms without having to develop an entire weapon system.
“The old way of doing things is dead,” Ruocco said. “That legacy model of closed, bespoke systems can’t operate at the level of speed, adaptability, or affordability to meet the operational demands.”
Ruocco said the department has moved beyond isolated demonstrations and now intends to scale successful MOSA practices across services, platforms, and operating domains. That effort will require common reference architectures, interface repositories, governance models, and a workforce that knows how to use them.
