GAO Weapon Systems Annual Assessment 2026 (GAO-26-108457)
The latest edition of the most detailed open dataset on US defense cost and schedule growth: GAO's 24th annual review of the Department of Defense's costliest weapon programmes. Here is what GAO-26-108457 found, the portfolio it covers, and how to cite it.
What the 2026 report found
GAO-26-108457 assessed 104 major US weapon programmes representing over $2.4 trillion in planned investment. The report's central finding is about schedule: the overall average time to deliver even an initial capability rose again this year, to over 12 years from a programme's start, and GAO expects it to climb further as programmes delay milestones. DOD is leaning on the middle tier of acquisition (MTA) rapid pathway, at least $49 billion across 23 programmes, but many entered it with immature technology, which undercuts the speed it is meant to deliver.
Source: US Government Accountability Office (2026). Weapon Systems Annual Assessment, GAO-26-108457, 2 July 2026.
What the 2026 assessment covers
Each year GAO reviews the Department of Defense's most expensive acquisition efforts and reports cost, schedule, and performance against their approved baselines. The 2026 edition assessed 104 of DOD's costliest weapon programmes, representing over $2.4 trillion in planned investment, and analysed how far selected programmes follow GAO's leading practices for product development (set out in GAO-23-106222). It is the closest thing to an audited, programme-by-programme public ledger of cost and schedule growth that exists for any government or industry.
This is GAO's 24th annual assessment, responding to a standing statutory requirement for GAO to review selected DOD acquisition programmes every year. It lands against the backdrop of DOD's November 2025 Acquisition Transformation Strategy, a new round of reforms intended to speed up delivery. GAO notes that in both June 2024 and June 2025 it had already found DOD struggling to execute earlier reforms with the same goal.
The 2026 story is schedule, not just cost
Where the 2025 edition led with a $49.3 billion one-year jump in cost estimates, the 2026 assessment's sharpest finding is time. GAO reports the overall average time to deliver even an initial capability increased again this year, to over 12 years from a programme's start. Because several major defense acquisition programmes have not set new delivery dates or are delaying interim milestones, GAO warns that keeping delivery dates static hides slippage rather than removing it, so the 12-year average is likely to rise further.
DOD's answer has been to route more work through the middle tier of acquisition (MTA), a rapid prototyping and fielding pathway meant to be completed in five years. But GAO found the pathway is being used for some of the largest and most time-consuming programmes, and that many programmes enter it with technology that is not ready: between 2018 and 2025, 18 of 40 programmes started the MTA pathway with immature technologies, and seven of eight programmes currently on the pathway still carry immature technologies that need more development. GAO recommended DOD require MTA-pathway programmes to start with mature technologies, or develop the immature ones separately; DOD concurred.
The 2026 edition against prior years and cross-sector datasets
The GAO assessment is the authoritative source for US defense cost and schedule growth specifically. Because the headline figures change every edition, cite the year and report number you mean. It sits alongside the cross-sector datasets that anchor the rest of this site.
| Study | Sample | Headline finding |
|---|---|---|
| GAO Weapon Systems Assessment (2026) | 104 major DOD programmes | Over $2.4T planned; avg time to initial capability now over 12 years |
| GAO Weapon Systems Assessment (2025) | 106 major DOD programmes | $49.3bn one-year cost-estimate rise; ~12 yrs to initial capability |
| Flyvbjerg project database (2023) | 16,000+ projects (all sectors) | Defense mean overrun high; only 0.5% deliver on budget, time and benefits |
| Standish CHAOS (2020) | 50,000+ project records | 31% successful, 50% challenged, 19% failed |
Cite the report number, not just “the GAO study”
GAO publishes a new Weapon Systems Annual Assessment every year, and the headline figures change with each edition. The 2026 edition is GAO-26-108457, published 2 July 2026, and it is the 24th in the series; the prior edition is GAO-25-107569 (2025). When quoting a figure such as the over-12-year average time to initial capability, cite the specific report number and year so the number stays traceable to the edition it came from.
Programme-level overrun figures for individual systems (F-35, Sentinel, Columbia-class, Ford-class) are collected on the defense projects page, which draws on this and prior GAO assessments.
How to cite
Primary source: gao.gov/products/gao-26-108457
The full report and a one-page Highlights summary are free on gao.gov. The Highlights PDF carries the headline figures; the GAO Weapons Acquisition portal lists every edition back to FY01.
Frequently Asked Questions
What is GAO-26-108457?
GAO-26-108457 is the US Government Accountability Office's 2026 Weapon Systems Annual Assessment, published 2 July 2026. It is the 24th edition of GAO's annual review of the Department of Defense's costliest weapon programmes, and it assessed 104 programmes representing over $2.4 trillion in planned investment.
How long do major US weapon programmes take to deliver?
GAO found the overall average time to deliver even an initial capability rose again in 2026, to over 12 years from a programme's start. Because several programmes have not set new delivery dates or are delaying interim milestones, GAO expects the 12-year average to increase further.
What did the 2026 report say about the rapid-acquisition (MTA) pathway?
DOD is investing at least $49 billion across 23 of its most expensive middle-tier-of-acquisition (MTA) programmes, a pathway meant to deliver in five years. GAO found the portfolio grew because larger, more time-consuming programmes used it, and that many entered with immature technology: 18 of 40 programmes between 2018 and 2025, and seven of eight currently on the pathway. GAO recommended DOD require mature technologies before starting, and DOD concurred.
How is the 2026 edition different from the 2025 one?
The 2025 edition (GAO-25-107569) led with a $49.3 billion one-year rise in combined cost estimates, driven largely by the Sentinel ICBM. The 2026 edition (GAO-26-108457) foregrounds schedule, an average time to initial capability now over 12 years, and the risk that leaning on the MTA rapid pathway with immature technology will not deliver the speed intended. Cite whichever edition your figure came from.
Where can I read the report?
It is free on gao.gov at gao.gov/products/gao-26-108457, with a full PDF and a one-page Highlights summary. GAO publishes a new edition each year, so cite the specific report number and year.