The AEI Defense Budget Navigator: A Complete Guide to America’s Defense Spending Data

Key Takeaways

• The AEI Defense Budget Navigator offers free, interactive access to decades of Pentagon spending data.
• FY2026 defense spending reached $961.6 billion, combining base and reconciliation funding.
• Continuing resolutions have cost the Pentagon an estimated $50-$70 billion in buying power over two years.

What the Defense Budget Navigator Is

The Defense Budget Navigator is a publicly accessible digital platform built by the American Enterprise Institute that allows anyone with an internet connection to explore, compare, and analyze United States defense spending data. It’s not a simple chart with a few data points. It’s a structured, multi-section tool that covers historical spending trends going back decades, detailed line-item budget data, an explanation of how budget requests move through the federal government, and a budget overview that lets users compare what each presidential administration requested against what Congress actually appropriated.

The Navigator sits within a broader ecosystem of defense research tools developed at AEI. It functions as the data backbone behind much of the policy analysis the institute produces on national security. Journalists, congressional staffers, students at graduate programs, and independent researchers all use it to ground their arguments in official figures rather than secondhand summaries. That’s genuinely valuable in a policy debate where numbers get quoted selectively, stripped of context, or compared across incompatible baselines.

Its five main sections are: the Dashboard (the entry point), Historical Trends, Budget Overview, Budget Details, and Process. Each section addresses a different question about the defense budget. The Dashboard orients the user. Historical Trends allows comparisons across decades. Budget Overview covers the top-line request broken out by military service and appropriation title. Budget Details reaches down to the line-item level, where individual programs are funded. The Process section explains how a presidential budget request gets transformed into actual law.

The Team Behind the Tool

Todd Harrison is a senior fellow at AEI, where he concentrates on defense strategy, defense budgeting, and space policy. He previously served as director of the Defense Budget Analysis program and the Aerospace Security Project at the Center for Strategic and International Studies and as a senior fellow for defense budget studies at the Center for Strategic and Budgetary Assessments. His academic background, including a BS and MS in aeronautics and astronautics from MIT, gives the Defense Budget Navigator’s data presentation a methodological rigor that’s relatively uncommon in policy tool design.

Harrison collaborates closely with Elaine McCusker and John G. Ferrari, who together have produced a substantial body of working papers under the AEI banner examining Pentagon organization, efficiency, procurement, and force structure. McCusker previously served as the Pentagon’s acting undersecretary of defense (comptroller), which means she’s spent real time inside the building managing the budget process that the Navigator describes from the outside. Ferrari retired as a major general in the U.S. Army and served as a director of program analysis and evaluation for the service. The three together represent an unusual combination of institutional knowledge, operational experience, and quantitative rigor.

That combination matters because the defense budget is not just a table of numbers. It reflects strategic choices, political constraints, institutional inertia, and decades-long acquisition timelines that interact in ways that aren’t obvious from a spreadsheet. Having people who’ve worked inside the system build the tool that explains the system makes a difference.

The Historical Trends Explorer

The Historical Trends section of the Navigator allows users to compare defense budget authority, outlays, personnel levels, and force structure across decades, with customizable views and downloadable results. That phrase “across decades” is doing a lot of work. The tool draws on data that goes back to the early post-World War II period, so a user can trace the arc of American defense spending from the Korean War buildup through the Cold War plateau, the post-Soviet drawdown, the post-9/11 surge, the Budget Control Act cuts, and the gradual climb that has continued through the 2020s.

From the end of the Korean War through the end of the Cold War, fiscal years 1954 through 1990, the United States averaged spending 6.6 percent of GDP on defense, and during this time the economy grew at a compound annual rate of 3.5 percent above inflation. From fiscal year 1991 through fiscal year 2023, the nation spent an average of 3.2 percent of GDP on defense, and the economy grew at a compound annual rate of 2.6 percent above inflation. That comparative data forms one of the core arguments that AEI researchers make about the sustainability of higher defense investment.

What the historical data reveals, viewed over the full postwar arc, is that the conventional wisdom about “record-high” defense budgets requires significant qualification. In inflation-adjusted dollar terms, yes, the numbers keep climbing. But as a percentage of GDP, the United States currently spends far less on defense than it did during most of the Cold War. Defense spending stood at 6.8 percent of GDP at the height of the Reagan defense buildup, declined to below 4 percent in 1996, and bottomed out at 3.5 percent of GDP in 2001, about half the level of 1985. In FY2025, defense spending was approximately 4.7 percent of GDP.

The distinction between budget authority and outlays is one that the Navigator explains and the Historical Trends section makes usable. Budget authority is the legal permission to obligate funds, and it’s what most news coverage reports when a “defense budget” figure is cited. Outlays are actual cash payments made in a given fiscal year. Because many defense contracts span multiple years, the outlay figure in any given year reflects obligations made years earlier. The Navigator lets users toggle between the two metrics, which prevents misleading comparisons between years or administrations that use different accounting approaches.

Personnel levels and force structure data add a dimension that pure spending figures miss entirely. Budgeted salaries and benefits for the 1.3 million active-duty and 800,000 reserve uniformed personnel for FY2025 total about $182 billion, reflecting the cost of an all-volunteer armed force as opposed to the cheaper alternative of conscription. The number of people in uniform has declined substantially since the Cold War even as spending has risen, which means cost per service member has increased dramatically. That tension between headcount and cost sits at the center of many force structure debates, and the Navigator’s personnel tracking makes it concrete.

Budget Overview and the Deep Dive

The Budget Overview section covers the full budget, while the Budget Details section allows users to search detailed Department of Defense budget data by title, service, request, and fiscal year, with drill-down charts that reach line-item level detail. This is where the Navigator becomes genuinely useful for anyone trying to track a specific program, understand why a particular service’s budget changed year-over-year, or verify a claim made in a congressional hearing.

The Budget Details section is probably the most technically demanding part of the Navigator to use well, but it’s also the most powerful. Defense budgets are organized by appropriation title (Military Personnel, Operations and Maintenance, Procurement, Research Development Test and Evaluation, and Military Construction are the main ones), by service (Army, Navy, Marine Corps, Air Force, Space Force), and by specific program element. A user who knows that the Navy’s shipbuilding account is called Shipbuilding and Conversion, Navy (SCN) can search for it directly and see year-over-year funding levels. Someone who wants to understand how the F-35 procurement budget has changed since the program’s early years can trace that too.

The ability to download data for external analysis matters more than it might seem. Policy researchers and budget watchdog organizations often need to run their own calculations, adjust for inflation using their preferred deflator, or combine defense data with other federal budget information. Tools that let users export to standard formats rather than locking data inside proprietary visualizations serve the broader goal of informed public debate.

The Budget Process Section

The Process section of the Navigator is probably the most underused part of the tool by casual visitors, and it’s probably the section that would do the most good if more people read it. The federal defense budget process is genuinely complicated, and that complexity creates substantial opportunities for confusion both unintentional and deliberate.

A presidential budget request is not a law. It’s a proposal. When the Department of Defense Comptroller’s office releases a budget document each spring, that document represents the executive branch’s wish list, not settled policy. Congress then runs its own parallel process, through both the authorization committees (the House Armed Services Committee and the Senate Armed Services Committee, which write the National Defense Authorization Act) and the appropriations committees (the House and Senate Subcommittees on Defense), which write the actual spending bills. Authorization tells the Pentagon what programs it’s allowed to pursue. Appropriations determines how much money those programs actually receive.

The two tracks are supposed to run in sequence, with authorization preceding appropriations, and both supposed to complete before October 1, the start of the new fiscal year. In practice, the Department of Defense has started the last 14 out of 15 fiscal years under a continuing resolution, enduring a total of 2,158 days during which it has been unable to move ahead on new programs and priorities. A continuing resolution (CR) funds the government at approximately the prior year’s enacted levels, which sounds benign but carries significant operational costs.

When the Pentagon operates under a CR, it can’t start new programs, it can’t ramp up production on existing ones, and it can’t realign funding between accounts even when circumstances change. In an environment where inflation has been running above the Pentagon’s projected rates, a flat funding level is effectively a real-terms cut. The Navigator’s process section explains this structural dynamic in terms that make clear why budget timing matters as much as budget levels.

The Defense Futures Simulator

Closely linked to the Defense Budget Navigator is the Defense Futures Simulator, a separate but complementary tool that allows users to go beyond analysis and into scenario construction. The Defense Futures Simulator (DFS) is an interactive online tool designed to empower scholars, policymakers, and practitioners to create and analyze defense strategies and budgets. DFS allows users to quickly iterate and explore alternative approaches, evaluating their impact on the budget and military force structure in real-time, and DFS is freely available to the public, allowing anyone to make an account and start creating scenarios.

In 2020, the American Enterprise Institute, War on the Rocks, and the Center for Strategic and International Studies collaborated to create the original Defense Futures Simulator. In 2024, AEI partnered with CSIS and Spear AI to launch a significantly enhanced version that includes advanced features such as user account creation, scenario saving, and scenario sharing.

The DFS is not a simple budget calculator. The model includes realistic constraints on how much and how fast a scenario can deviate from the baseline to account for industrial base capacity and other practical limitations. DFS considers both the direct and indirect costs of changes, including procurement, research and development, operations, sustainment, and personnel expenses. It also tracks critical force metrics, such as total Air Force aircraft numbers or Navy ship count and tonnage.

One of the more distinctive features is the political sensitivity rating system. Users can assess the political sensitivity of budget choices through a unique “chili pepper” rating system that estimates the overall political risk associated with a set of decisions. The tool also includes a cross-scenario comparison tool, which visually illustrates the similarities and differences between scenarios, and quantifies the degree of commonality between them. All reports include an export function to PDF and Excel to facilitate external analysis.

The DFS has moved from being a curiosity for defense wonks to a practical tool used in real policy exercises. In March 2025, AEI’s Todd Harrison and CSIS’s Seamus P. Daniels hosted a panel where experts including Michael O’Hanlon of the Brookings Institution used the Defense Futures Simulator to process cuts and reinvestments consistent with Defense Secretary Pete Hegseth’s guidance on an 8 percent budget reduction. Broad themes from the experts’ decision-making included cuts to the Army, largely reinvested in the Navy and the other services, and investments in air and missile defense and missiles and munitions at the cost of other categories not related to lethality.

Johns Hopkins University’s School of Advanced International Studies has used the DFS as the centerpiece of its graduate course requiring teams to construct a full U.S. defense strategy with a five-year detailed budget plan. DFS is built to continuously learn and improve as it is used, and it is not limited to just the U.S. military, with baseline data for additional countries expected to be added over time.

The FY2026 Defense Budget

The fiscal year 2026 defense budget request represents one of the most unusual in recent memory, and the Defense Budget Navigator is well-positioned to put it in context. The Defense Department unveiled a $961.6 billion request for fiscal 2026, framing the budget as a historic investment that prioritizes strengthening homeland security, deterring Chinese aggression in the Indo-Pacific, revitalizing the U.S. defense industrial base, and maintaining stewardship of taxpayer dollars.

That headline figure requires explanation because it combines two fundamentally different types of funding. Of the $961.6 billion total, $848.3 billion is allocated for the DoD’s discretionary budget, and $113.3 billion is provided through mandatory reconciliation funding. Here’s how the budget breaks down by service: the Army is allocated $197.4 billion, the Navy $292.2 billion, the Air Force $209.6 billion, the Space Force $39.9 billion, and $170.9 billion is designated for defense-wide activities.

The table below summarizes the FY2026 defense budget request by service component:

The FY2026 budget marks the first year in which the DoD has dedicated a separate budget line for autonomy and AI systems, totaling $13.4 billion. These funds cover unmanned and remotely operated aerial vehicles ($9.4 billion), autonomous ground vehicles ($210 million), maritime autonomous systems ($1.7 billion), underwater capabilities ($734 million), and supporting software and cross-domain integration ($1.2 billion).

Space Force received especially large treatment. Despite earlier reports that the FY2026 request would shrink the Space Force budget to $26.6 billion, the administration changed course and instead sought nearly $40 billion, more than a 30 percent jump from FY2025 levels.

The Reconciliation Question

The most significant structural feature of the FY2026 defense budget, and the one the Defense Budget Navigator’s process section helps explain, is its unprecedented reliance on budget reconciliation as a source of defense funding.

The FY2026 budget request takes a novel approach through reconciliation. The Trump administration proposed a base discretionary defense budget that is flat in nominal terms at $848 billion, matching the Fiscal Responsibility Act level for FY2025. Rather than facing the mismatch between flat budgets and rising costs, the administration leveraged the anticipated defense funding Congress tucked into the reconciliation bill.

Reconciliation is a congressional procedure designed primarily to align revenues and spending with budget resolutions. It requires only a simple majority in the Senate rather than the 60 votes typically needed to advance legislation. For decades, defense spending was kept entirely out of the reconciliation process. By setting the military budget through reconciliation, Congress increases the likelihood that future lawmakers will circumvent the regular NDAA process, because if they can approve a military budget with fewer votes in the Senate, they will. The NDAA process is far more deliberative and transparent than reconciliation, which is largely a partisan practice carried out behind closed doors.

At the heart of the issue is the broader budget reconciliation process, which for the first time ever includes money, in this case $150 billion for defense procurement and readiness. This represents a historical shift by the Congress in declaring its intent to resource “Peace through Strength,” and the military services along with the tech industrial base need this money.

The oversight implications are real. The Department of Defense submitted a fully classified spending plan for $90 billion of the $150 billion budget appropriated for national security after the reconciliation bill passed in July 2025 and was signed by President Donald Trump. Money was said to go toward the Golden Dome project, shipbuilding, and weapons procurement. Congress has yet to receive a spending plan for the remaining $60 billion, with some members questioning the budget’s intent and lack of oversight.

The Defense Budget Navigator’s process and detail sections are designed precisely for moments like this. When significant amounts of defense money are being obligated through mechanisms that bypass traditional budget documentation and justification, having a tool that tracks line-item data against presidential requests becomes an accountability resource rather than just an analytical convenience.

Continuing Resolutions and the Cost of Dysfunction

One of the clearest conclusions that emerges from sustained engagement with the Defense Budget Navigator’s historical and process data is that the formal budget process has been broken for a long time, and the costs are tangible and measurable.

In fact, 2025 was a new threshold of failure, as an annual funding bill was never passed, followed by the longest government shutdown in history. Depending on how one calculates all the variables, the taxpayer has lost between $50 and $70 billion in buying power under continuing resolutions in the past two years alone.

That’s not an abstract accounting entry. It translates to ships not contracted, munitions not purchased, and maintenance not scheduled. When the Navy can’t ramp up production on a submarine because a CR prevents it from starting new contracts, the shipyard doesn’t sit idle: it finds other work, trains workers for other programs, and loses the institutional momentum that’s expensive to rebuild. The Congressional Budget Office has documented that stop-start funding cycles systematically increase program costs, and the Navigator’s historical data makes that pattern visible over time.

The Pentagon was operating under its first-ever year-long continuing resolution when the FY2026 budget was being developed. Seven months into a presidential transition year, the 2026 budget request was very late, partly due to an aggressive exercise to realign money toward key military priority areas and a wave of executive orders and DOGE-influenced efficiency reviews, the full impacts of which remained pending.

Whether or not one agrees with the specific priorities that any given administration sets for defense, the argument that annual appropriations uncertainty imposes real costs on military readiness is supported by the data the Navigator compiles. It’s one of those policy positions that’s difficult to contest once the numbers are laid out over time.

Readiness vs. Modernization

A persistent tension visible throughout the Defense Budget Navigator’s data is the tradeoff between near-term readiness and long-term modernization. These two budget priorities compete for the same pot of money, and the history of American defense budgeting is in large part a history of oscillating between them.

The FY2025 defense budget traded modernization for readiness. Compared to the Pentagon’s projections from the year before, procurement was reduced by 4.4 percent and research and development by 1.3 percent. That’s the kind of trend the Navigator makes visible when you can place the FY2025 procurement figures against a 10-year baseline. Any single year looks modest. Traced over a decade, the compounding effect of consistently underfunding modernization becomes obvious.

The Army faced some of the sharpest cuts. In the FY2025 request, Army modernization would decline by 2.4 percent. It was the only service with cuts to its operations and maintenance budget. Alongside growing personnel costs and recruiting difficulties, the Army continued to shrink to 442,300 soldiers in 2025, the smallest since 1940.

The Navy’s situation was equally concerning from a long-term perspective. The Navy’s requested shipbuilding budget asked for $32.4 billion, $400 million less than the year before. As a result, the Navy planned on buying just six battle force ships, the smallest quantity bought by any administration since 2006. Alongside that, the Navy planned on retiring 19 ships, meaning the fleet was expected to shrink from 296 ships to 287, a net loss of 9 ships.

The Air Force trajectory showed a similar pattern. The Air Force’s FY2025 request called for just 91 new aircraft while retiring 250. Fighter procurement was slashed, with F-35 procurement declining from 48 to 42, and the F-15EX from 24 to 18. According to Air Force officials, this reduction was exclusively due to fiscal constraints.

These cuts don’t represent isolated choices by specific administrations. They reflect the structural math of a defense budget in which personnel and operations costs have grown faster than the overall top line for years, steadily crowding out investment accounts. The Navigator’s deep-dive data section lets anyone trace that pressure across service budgets and appropriation titles over time.

The Space Force and Emerging Technology

The FY2026 figures for the U.S. Space Force represent one of the most significant single-year budget increases in the history of any military service. Going from approximately $30 billion to nearly $40 billion in one year reflects the administration’s bet that space-based capabilities, particularly missile defense, represent the decisive investment of this strategic moment.

The FY2026 budget makes clear that space is central to the administration’s defense priorities. Key among these is the Golden Dome, President Trump’s comprehensive missile defense initiative designed to defend the United States from advanced aerial threats including ballistic, hypersonic, and cruise missiles. Designed as a multi-layered, space-integrated defense system, Golden Dome is expected to be fully operational by 2028. An initial investment of $25 billion has been earmarked for it, intended as a down payment toward the system’s projected $175 billion total cost.

Whether that projected cost figure will hold is genuinely uncertain. The history of major defense acquisition programs, as visible in the Budget Navigator’s historical procurement data, suggests that cost growth is far more common than cost discipline. The Sentinel ICBM program, for example, triggered a Nunn-McCurdy review after costs ballooned. The Congressional Budget Office estimated the United States will spend $946 billion over the next decade on nuclear modernization, operations, and sustainment, with $129 billion of that representing likely cost growth above programmatic estimates.

The first-ever separate budget line for AI and autonomy systems in FY2026 signals that these technologies are graduating from experimental programs to funded force structure. Whether the $13.4 billion allocation is adequate to the task is debated, but the decision to establish a distinct account rather than burying autonomous systems funding within existing program elements is itself a meaningful structural change that the Navigator’s detailed tracking will make easier to follow in future years.

Historical Peaks, Troughs, and What They Mean

America’s per capita defense spending over the postwar era has been basically stable since the early 1950s, oscillating up and down in almost regular waves around an almost fixed mean. Defense spending has exceeded the long-term mean in four of these waves: during and just after the Korean War, during the Vietnam War, during the Reagan-Bush push that saw the Cold War to its end, and during the Iraq and Afghanistan surge years.

That long-run stability in per-capita terms is counterintuitive but important. It suggests that the United States has a kind of implicit political equilibrium around defense spending, a range within which public tolerance oscillates depending on perceived threat levels and competing domestic priorities. The current moment sits at the upper end of what peacetime politics has historically sustained, but not dramatically above it.

History suggests that spending as much as 6 percent of GDP on defense can be sustained over time without causing economic harm, but spending more than 10 percent of GDP should be reserved for periods of crisis. By each of the measures tracked through the Navigator, U.S. defense spending is on a sustainable trajectory with ample room for growth.

The international comparison data, which the Navigator contextualizes through AEI research drawing on Stockholm International Peace Research Institute figures, shows that while the United States spends more than any other nation in absolute dollar terms, it spends less as a share of GDP than Ukraine, Russia, Saudi Arabia, and Israel. Estimates for China’s defense spending range from $309 billion to $711 billion in 2022 U.S. dollars, suggesting that although China is catching up, the United States still spends more on defense than any other nation.

The spread in those estimates for China illustrates why the Navigator’s transparency and methodological documentation matter. Defense budget comparisons across countries involve different accounting systems, different personnel cost structures, and different definitions of what counts as defense spending. The AEI team documents these caveats explicitly, which is more than most sources providing defense comparisons do.

The DOGE Efficiency Exercise

The FY2026 budget arrived in a context shaped partly by the Department of Government Efficiency (DOGE) review, which affected Pentagon operations alongside the rest of the federal government. AEI researchers published a series of working papers examining where the Department of Defense could find real savings without sacrificing military capability, including analyses of procurement reform, organizational decentralization, and specific contracting inefficiencies.

The federal budget is large enough, with enough pieces, rules, and priorities, that it’s easy to get lost in it. While everyone wants the government to run effectively and to use taxpayer money wisely, the moving parts make it difficult to decipher what is happening and how it impacts national security. The AEI working papers and the Navigator together address precisely that problem, one at the analytical level and the other at the data access level.

The distinction between genuine efficiency gains and simple budget cuts that degrade capability is not always easy to draw from the outside. The Defense Budget Navigator’s line-item tracking makes it possible, over time, to test whether claimed efficiencies show up as sustained readiness improvements or just as smaller numbers in accounts that matter for combat effectiveness.

Force Structure and the Budget Navigator’s Tracking

Force structure is the link between defense budget numbers and actual military capability. How many ships the Navy has, how many aircraft the Air Force can fly, how many brigades the Army can deploy: these are the concrete outputs that defense spending is supposed to produce. The Budget Navigator’s force structure tracking makes it possible to watch how spending levels translate, or sometimes fail to translate, into maintained military capacity.

Force structure is one of the biggest cost factors in the department’s spending and a target for savings, as noted by experts using the Defense Futures Simulator in exercises designed to identify budget adjustments consistent with an 8 percent reduction scenario. The Navy’s submarine program, modernizing the nuclear triad, and increasing operational readiness for all services received the biggest recommended increases in those exercises. U.S. Army force structure suffered the biggest recommended cuts.

That finding from the DFS exercises is consistent with the broader strategic consensus that the most likely high-end conflict scenarios, particularly in the Indo-Pacific, favor naval and air forces over large ground forces. The Budget Navigator’s historical force structure data lets anyone trace how the Army has evolved since the Cold War, from a force designed to hold a large conventional front in Europe to a smaller, more deployable but less mass-capable institution.

The specific choice to shrink the Army while investing in submarines and missiles isn’t obviously correct or obviously wrong. There’s a legitimate argument that ground forces remain the ultimate guarantor of territorial control in ways that naval and air power can’t fully replace. But the trajectory visible in the Navigator’s data suggests that the political system has been making that choice implicitly for decades, and the FY2026 budget makes it more explicit.

What the Navigator Gets Right (and What It Can’t Do)

The Defense Budget Navigator does several things extremely well. It aggregates official data from sources including the Office of the Under Secretary of Defense Comptroller, the National Defense Budget Estimates (the “Green Book”), and congressional appropriations documents, and makes that data accessible without requiring users to track down and reconcile multiple government publications. The historical continuity is especially valuable: being able to compare FY2010 procurement figures directly against FY2026 figures, adjusted for inflation, without having to manually download and harmonize multiple Green Book editions, saves researchers substantial time.

It also explains the budget process honestly. The gap between what a president requests and what Congress appropriates, and the further gap between what Congress appropriates and what the Pentagon actually spends in a given year, are not always made clear in public discussion. The Navigator’s process section addresses this.

Where it faces inherent limitations is in capturing information that isn’t in the official budget documents at all. Classified programs, of which the FY2026 budget has an unusually large share, don’t appear in the public budget documentation and thus can’t appear in the Navigator. The $60 billion in reconciliation money that lacks a public spending plan is a good example: it exists as a number in the top line, but the Navigator can’t tell users what it’s actually being spent on because that information hasn’t been made public.

The final outcome of the fiscal year 2026 federal budget process remains uncertain. Continuing resolutions, potentially for the entire year, are a strong possibility. The specter of a complete process breakdown and a government shutdown also looms as political disagreements persist while the fiscal year clock runs out. These uncertainties are the kind of real-time political dynamics that no data tool can fully capture while they’re still unresolved.

Why Defense Budget Literacy Matters

The Defense Budget Navigator’s deepest value is in making a highly technical and politically contested subject legible to people who didn’t spend careers inside the Pentagon or on the Hill. Defense spending decisions affect everything from the production volume at shipyards in Connecticut and Newport News to the readiness of bases in South Korea to the pace of nuclear modernization. The money involved, whether one uses the $848 billion discretionary figure or the $961 billion total including reconciliation, is large enough to matter for the national debt, for what gets crowded out in the discretionary budget, and for whether allied nations take U.S. security commitments seriously.

The United States accounts for nearly 40 percent of global military spending and devotes a larger share of its GDP to defense than most other major industrial countries. Personnel costs account for nearly half of all defense spending, while most of the other half goes toward procurement, research, development, and testing.

Those ratios matter for understanding where potential efficiencies lie and what the actual military output of the budget is. A budget that’s half personnel costs produces a different force than one that’s half procurement, even at the same top-line number. The Budget Navigator’s appropriation-title breakdowns make this visible.

The $150 billion reconciliation supplement, the classified Golden Dome investment, the Space Force budget nearly doubling in a single year, the Army continuing to shrink toward its smallest size since 1940: none of these trends is easy to understand in isolation, and each is being discussed in political contexts where the incentive to simplify is strong. Congress should work with the White House to develop and pass another budget reconciliation bill with defense spending in 2026, and Pentagon leadership should engage now to make sure the legislation contains funding for what the military needs most.

Whether that view prevails or not, the ability to test claims about defense spending against actual historical and current data, rather than taking assertions at face value, is what the Defense Budget Navigator enables. In a policy debate where numbers are frequently cited without context, that’s a service with real public value.

Summary

The AEI Defense Budget Navigator is a data tool that works because it was built by people who understand both the substance of defense policy and the limitations of public budget documentation. It doesn’t advocate for a particular spending level or strategic orientation; it makes the data available in a form that supports informed analysis from any starting position. Its five sections, historical trends, budget overview, deep-dive details, process explanation, and the dashboard that ties them together, address the actual questions that arise when someone tries to engage seriously with how the United States allocates resources for national defense.

The current budget moment is an unusually complex one. FY2026 combines a flat discretionary base with a historically unprecedented reconciliation supplement, a rapidly expanding Space Force account, the first standalone AI and autonomy budget line, and significant classified spending that exists outside the public documentation the Navigator tracks. That combination makes the Navigator’s historical context more important than ever: understanding where the current budget sits relative to Cold War norms, post-9/11 peaks, and the Budget Control Act cuts of the 2010s is the only way to assess whether any given claim about current spending levels being “historic” or “insufficient” is grounded in reality or rhetoric.

The fact that the tool is free, publicly accessible, and continuously updated makes it unusual in a space dominated by paywalled databases and proprietary research products. As defense spending debates intensify around questions of China competition, nuclear modernization, AI-enabled warfare, and the sustainability of existing alliances, the value of having a shared factual baseline that both sides of those debates can draw on is underappreciated. That’s ultimately what the Defense Budget Navigator offers, and it’s something the broader defense policy conversation genuinely needs.

Appendix: Top 10 Questions Answered in This Article

What is the AEI Defense Budget Navigator?

The AEI Defense Budget Navigator is a free, publicly accessible online tool built by the American Enterprise Institute that allows users to explore, compare, and analyze U.S. defense spending data. It covers historical budget trends, line-item program details, top-line service allocations, and the federal budget process from presidential request through congressional action.

Who built the Defense Budget Navigator and what are their credentials?

The tool was built primarily by Todd Harrison, a senior fellow at AEI who previously led defense budget analysis at the Center for Strategic and International Studies, working alongside Elaine McCusker, who served as the Pentagon’s acting undersecretary of defense (comptroller), and retired Army Major General John G. Ferrari, who previously directed program analysis and evaluation for the Army.

What is the total FY2026 U.S. defense budget request?

The FY2026 defense budget request totals $961.6 billion, combining $848.3 billion in discretionary base funding with $113.3 billion in mandatory reconciliation funding. When including the full $150 billion reconciliation allocation plus the National Nuclear Security Administration portion, total national security spending surpasses $1 trillion.

What is the Defense Futures Simulator and how is it related to the Navigator?

The Defense Futures Simulator is a complementary interactive tool built by AEI, the Center for Strategic and International Studies, and War on the Rocks in 2020 and substantially enhanced in 2024 with Spear AI. It lets users create alternative defense budget and strategy scenarios, tracking the impact on force structure, service funding levels, and political feasibility using a “chili pepper” risk-rating system.

How has the U.S. defense budget changed as a percentage of GDP since the Cold War?

During the Cold War, from fiscal years 1954 to 1990, the United States averaged 6.6 percent of GDP on defense. After the Soviet Union’s collapse, spending fell to 2.9 percent of GDP by 2000. It climbed back during the post-9/11 surge to approximately 5.7 percent of GDP in 2010 to 2011, then declined again. In FY2025, defense spending stood at approximately 4.7 percent of GDP.

What is a continuing resolution and why does it harm the Pentagon?

A continuing resolution (CR) is a stopgap measure Congress uses to fund the government at the prior year’s enacted spending levels when it fails to pass regular appropriations bills before October 1. Under a CR, the Defense Department cannot start new programs, ramp up production contracts, or realign funding between accounts. The DoD has started 14 of the last 15 fiscal years under a CR, losing an estimated $50 to $70 billion in buying power over the two most recent years alone.

What is the reconciliation defense funding mechanism and why is it controversial?

Budget reconciliation is a legislative procedure that requires only a simple Senate majority rather than the usual 60 votes. The $150 billion in defense reconciliation funding signed into law in July 2025 marks the first time defense spending has been channeled through this mechanism, raising concerns about reduced transparency and oversight compared to the regular National Defense Authorization Act process. A significant portion of the spending plan remains classified.

How does the FY2026 Space Force budget compare to previous years?

The Space Force budget in FY2026 was requested at nearly $40 billion, representing a jump of more than 30 percent from FY2025 levels. This increase reflects the administration’s priority on Golden Dome missile defense, space-based capabilities, and achieving what officials describe as space superiority.

What has happened to the size of the Army under recent defense budgets?

The Army has been shrinking steadily as a result of budget constraints and strategic reprioritization. In FY2025, the Army continued contracting to 442,300 soldiers, the smallest active-duty force size since 1940. It was the only service with cuts to its operations and maintenance budget in FY2025, and its modernization budget declined by 2.4 percent that year.

What are the main sections of the Defense Budget Navigator and what does each cover?

The Navigator has five main sections. The Dashboard serves as the entry point. Historical Trends allows comparison of budget authority, outlays, personnel, and force structure across decades. Budget Overview covers the top-line request broken out by service and appropriation title. Budget Details provides line-item data searchable by program, service, and fiscal year. The Process section explains how the presidential budget request moves through Congress to become law or gets superseded by continuing resolutions.