Operations and Maintenance Definition (2025 Data) | Glossary
Operations and maintenance (O&M) refers to military spending on running, sustaining and supporting armed forces, distinct from procurement or personnel pay, set against a 2025 world total of $2,740.0bn across 149 countries.
Key takeaways
- Operations and maintenance (O&M) is spending on running and sustaining existing armed forces — fuel, repairs, training and upkeep — distinct from procurement (new equipment) or personnel (pay and benefits).
- The 2025 world military expenditure total is $2,740.0bn, summed across the 149 countries SIPRI reports data for.
- The $2,740.0bn total is our calculation from SIPRI country-level data, not a figure SIPRI itself publishes.
- Coverage gaps mean the total is a floor: some spenders, such as North Korea, have no SIPRI series.
Verdict
Operations and maintenance (O&M) is the military budget category for running and sustaining existing forces — fuel, repairs, training and upkeep — distinct from procurement or personnel costs. It sits within the $2,740.0bn world military expenditure total for 2025, our calculation from SIPRI country-level data covering 149 countries, which is a floor rather than a complete global figure due to coverage gaps.
At a glance
| World military expenditure | $2,740.0bn2025, constant 2024 USD |
|---|---|
| Countries included | 149SIPRI-reported 2025 series |
| Data year | 2025Actual figure, not an estimate |
| Attribution | Our calculationSummed from SIPRI country-level data |
Operations and maintenance (O&M) is the military-budget category covering the day-to-day cost of running and sustaining armed forces — fuel, repairs, training, spare parts and base upkeep — as distinct from buying new equipment or paying salaries. It sits inside the $2,740.0bn world total for 2025 — our calculation from SIPRI country-level data across 149 reporting countries — used throughout this site.
01 What Does Operations and Maintenance Mean?
O&M is one of the standard functional categories analysts use to break down a military budget, alongside personnel, procurement, and research and development. It covers the recurring costs of keeping existing forces operational: fuel and utilities, equipment repair and overhaul, spare parts, training exercises, facility upkeep, and contracted logistics support. It excludes the purchase price of new weapons systems (procurement) and the wages, pensions and benefits paid to service members (personnel costs).
02 O&M in the Context of Total Military Spending
To give the term scale, it helps to see the total budget it sits inside. SIPRI reports military expenditure data for 149 countries in 2025, and summing those figures gives a world total of $2,740.0bn.
| Metric | Value |
|---|---|
| World military expenditure, 2025 | $2,740.0bn |
| Countries included in the total | 149 |
This total is our calculation from SIPRI country-level data. Not SIPRI's own published total.
Within any national budget, O&M typically ranks among the largest functional categories, often on par with or exceeding personnel costs in advanced militaries with capital-intensive equipment fleets.
03 What O&M Spending Typically Covers
- Equipment sustainment — repair, overhaul and spare parts for existing vehicles, aircraft, ships and weapons systems.
- Fuel and utilities — the energy costs of operating bases, vessels and aircraft.
- Training and exercises — the recurring cost of keeping forces combat-ready, including joint exercises and simulator use.
- Facilities upkeep — maintenance of barracks, airfields, depots and other installations.
- Contracted logistics and support services — outsourced maintenance, transport and supply-chain functions.
04 How O&M Differs from Procurement and Personnel Costs
Military budgets are conventionally split into functional categories, and O&M is defined by contrast with the other two major ones:
| Category | What it covers |
|---|---|
| Operations and maintenance | Running and sustaining existing forces: fuel, repairs, training, upkeep |
| Procurement | Buying new equipment, weapons systems and platforms |
| Personnel | Salaries, pensions and benefits for service members |
A country can increase total military expenditure — such as the $2,740.0bn world total recorded across 149 countries in 2025, our calculation from SIPRI country-level data — by raising spending in any one of these categories. O&M spending tends to rise with the size and age of an existing force structure, since older equipment generally costs more to sustain, while procurement spending tracks acquisition programmes and personnel spending tracks force size and pay scales.
05 Data Coverage and Limitations
The $2,740.0bn figure is a sum of the 149 countries SIPRI reports for 2025, expressed in constant 2024 US dollars.
Sum of the 149 countries SIPRI reports for 2025. Some spenders are absent from the dataset (North Korea has no series; several states have gaps), so this is a floor, not the whole world.
Readers seeking country-specific O&M line items should consult that country's own defense budget documentation alongside the totals shown in the 2025 world rankings.
06 Related Glossary Terms
O&M is one of several standardized terms used to describe military budgets. For definitions of related categories and how they roll up into total military expenditure, see the full Glossary.
Frequently Asked Questions
- What does operations and maintenance mean in a military budget?
- Operations and maintenance (O&M) is spending on running and sustaining existing armed forces — fuel, equipment repair, training, facilities upkeep and logistics support — separate from buying new equipment (procurement) or paying service members (personnel).
- How does O&M relate to the 2025 world military spending total?
- O&M is one functional slice within total military expenditure. The 2025 world total, summed across the 149 countries SIPRI reports, is $2,740.0bn — but the dataset does not break that figure down into O&M, procurement and personnel shares.
- Is the $2,740.0bn figure published by SIPRI?
- No. It is our calculation from SIPRI's country-level data for 2025, not a total SIPRI itself publishes.
- Does the $2,740.0bn total cover every country in the world?
- No. It covers the 149 countries SIPRI reports data for in 2025. Some spenders, such as North Korea, have no SIPRI series, and several states have data gaps, so the total is a floor rather than a complete global figure.
defensebudget.org
Defense spending data, sourced from SIPRI
defensebudget.org tracks military expenditure for 160 countries using the SIPRI Military Expenditure Database. Pages are generated from that dataset and reviewed before publication.