GAO-25-106931
A modular open systems approach (MOSA) is a strategy that can help the Department of Defense (DOD) design weapon systems that take less time and money to sustain and upgrade. Recent legislation requires acquisition programs to implement a MOSA to the maximum extent practicable. GAO found that 14 of the 20 programs it reviewed reported implementing a MOSA to at least some extent. Other programs cited barriers to doing so, such as added cost and time to conduct related design work. While a MOSA has potential benefits, it may also require programs to conduct additional planning, such as to ensure they address cybersecurity aspects related to a MOSA.
A “modular open systems approach” allows DOD to easily add or replace weapon parts over time—similar to plug-and-play computer parts.
Deciding on this kind of approach early helps DOD save time and money on upgrades and maintenance later. DOD often cited short-term costs as a hurdle to this approach. But it didn’t analyze whether those costs outweighed potential long-term benefits like faster upgrades.
Also, DOD doesn’t consistently coordinate these types of design decisions across weapon programs—possibly missing opportunities to save money by sharing common parts.
We recommended that DOD improve how it uses modular open systems approaches.
The Army’s Future Long Range Assault Aircraft Is Using a Modular Open System Approach:
Year published: 2025
URL: https://www.gao.gov/products/gao-25-106931