A new report from the U.S. Government Accountability Office found that several major U.S. weapon systems are becoming significantly more expensive to operate and maintain, with some programs seeing steep cost increases and missed opportunities for savings.

In the report, the GAO found the department identified 14 weapon systems with what it classifies as “critical” operating and support cost growth out of 36 systems reviewed in fiscal years 2023 and 2024. The report defines the critical threshold as “at least a 25% increase” over recent estimates or “at least a 50% increase” over original baselines.

Operating and support costs, which cover everything from maintenance to personnel, are about 70% of a system’s "total life-cycle cost,” according to the report.

Among the most common drivers noted in the report were extended service lives and expanded procurement. In total, "12 of the 14 systems reported extensions to the service or program life."

Additionally, many programs saw cost increases because they incorporated “previously omitted costs,” including maintenance, spare parts, and upgrades that were not fully accounted for in earlier estimates.

Despite some progress addressing earlier cost growth, the GAO identified the Common Remotely Operated Weapons Station (CROWS) as a key shortfall in the Army’s response to maintenance issues.

The U.S. Army has not fully implemented a software update intended to fix a major maintenance problem with CROWS. 

The GAO warned that without ensuring that its units fully implement the software update, the Army is "missing an opportunity” to resolve operational issues and reduce costs.

Completing the update could generate substantial savings. The report estimates it would yield cost savings of "more than $130 million over the program’s remaining approximately 30 years of life."

The report marks the final GAO review required under a congressional mandate that dates back to 2021. A provision in the National Defense Authorization Act for fiscal 2026 eliminates the requirement for the Pentagon to report detailed cost-growth data in future "sustainment" reviews.

Despite this, watchdog officials emphasized that tracking these costs remains essential. 

The Defense Department “spends tens of billions of dollars to sustain its weapon systems,” the report noted.