The US nuclear triad is the three-legged structure of strategic forces maintained since the early 1960s: land-based intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles on missile submarines, and heavy bombers. The fiscal 2026 budget request includes roughly $60 billion across the nuclear enterprise to sustain the force and recapitalize all three legs, per a Congressional Research Service primer.
What are the three legs, and what replaces them?
Each leg is undergoing its largest replacement in generations, and the replacements overlap in the same budget decade. The Air Force is developing the Sentinel ICBM, previously known as the Ground-Based Strategic Deterrent (GBSD), to replace all Minuteman III missiles, with plans to acquire 659 missiles to support testing and deployment; the National Nuclear Security Administration is developing the W87-1 warhead to deploy on it, per CRS In Focus IF10519. In 2024, DOD conducted a congressionally mandated review of the Sentinel program after its costs rose sharply — a reminder that recapitalization carries program risk, not just sticker prices.
The sea leg is the most expensive single piece. The Navy is procuring 12 Columbia-class submarines, each featuring 16 SLBM tubes, to replace the existing Ohio-class fleet; the lead boat was supposed to begin patrols in fiscal 2031, but the Navy has stated that date is delayed. The Columbia-class drew a $9.6 billion discretionary request plus $1.9 billion assumed from mandatory funding in reconciliation legislation in the FY2026 budget.
The air leg spans the oldest and newest aircraft in the force. The current bomber fleet consists of B-2s and nuclear-capable B-52s — the B-1 no longer carries nuclear weapons — and the Air Force is acquiring the B-21 Raider bomber for conventional and nuclear missions, planning to procure a minimum of 100 of the bombers, which are currently in testing and initial production. The B-21 request drew $5.8 billion discretionary plus $4.5 billion mandatory in the same budget. The service is also pursuing a new long-range standoff cruise missile and life-extensions of the B61 bomb family.
| Leg | Current system | Replacement |
|---|---|---|
| Land | Minuteman III ICBM | Sentinel (LGM-35A), 659 missiles planned, plus W87-1 warhead |
| Sea | Ohio-class SSBN with Trident D-5 SLBM | Columbia-class SSBN, 12 boats planned |
| Air | B-2 and nuclear-capable B-52 | B-21 Raider, minimum of 100 planned |
What does modernization cost?
The headline numbers are large and cumulative. The Congressional Budget Office estimated that US programs to operate and modernize nuclear forces would cost $946 billion over the next ten years, per the CRS primer. Within that, DOD's FY2026 request includes about $60 billion across the nuclear enterprise — a figure that covers both day-to-day sustainment of the existing force and the major recapitalization now underway across all three legs.
The simultaneous replacement of all three legs is historically unusual. Past recapitalizations were staggered across decades; this one overlaps, compressing budgets, shipyard capacity, bomber production, and the National Nuclear Security Administration's warhead work into the same window. That compression is why even successful programs strain the accounts: Columbia must be built while Ohio-class boats still patrol, and B-21 production must ramp while B-52s receive new engines and radar to remain credible into the 2040s.
How do treaties shape the force?
Since 2011, the New START treaty has capped deployed strategic forces, and its counting rules defined the force's public size for over a decade. The United States reported 1,419 warheads deployed on 662 missiles and bombers as of March 1, 2023, per a State Department fact sheet cited by CRS; as of September 1, 2022, the accountable force included 400 Minuteman III ICBMs among 450 operational launchers, 12 operational ballistic missile submarines, and the B-2 and nuclear-capable B-52 fleets.
The treaty's limitation period runs through February 5, 2026 — days after this article — and what verification, if any, follows it remains unresolved between Washington and Moscow as of this writing. The treaty context matters for force structure decisions: without negotiated limits, the size and composition of the arsenal become purely budgetary and doctrinal questions for Congress and the executive branch.
Why does the United States keep three legs?
The case for the triad is redundancy across different failure modes. Submarines are difficult to locate and destroy in a first strike; ICBMs force an adversary to strike hundreds of targets simultaneously, complicating any attack calculation; bombers are recallable in flight and visible as signals in a crisis. Together, the argument runs, they remove any adversary's confidence that a disarming strike is possible.
The counterargument, debated in Congress every budget cycle, is cost — sustaining three delivery systems, their command-and-control, and the warhead infrastructure behind them is the most expensive category of defense investment, and each leg has constituencies and skeptics. The CRS primer notes that some members of Congress have shown strong interest in conducting oversight of modernization efforts, and program-level reviews — such as the 2024 Sentinel review — are where that oversight becomes concrete.
How did the force get to this size?
The historical arc is steep. At the end of the Cold War in 1991, the United States deployed more than 10,000 warheads on strategic delivery vehicles. With the implementation of New START completed in February 2018, the United States was limited to 1,550 accountable warheads on those delivery vehicles — a reduction of roughly 85 percent from the Cold War peak, per CRS report RL33640, U.S. Strategic Nuclear Forces: Background, Developments, and Issues, which documents the drawdown and the acquisition plans of the 2020s in detail.
That history explains the current moment: the delivery systems built to implement the last wave of arms control are now reaching the end of their service lives together, which is why recapitalization is simultaneous rather than sequential. The triad the country built in the 1960s and modernized in the 1980s is being replaced nearly in full, and the bill for doing so arrives in annual installments of roughly $60 billion.
What could change the trajectory?
The plan is set, but its pace is not guaranteed, and the documented record already shows stress. The Navy has stated that the lead Columbia-class boat's patrol start, once planned for fiscal 2031, is delayed — a consequential slip, because the oldest Ohio-class boats cannot simply serve indefinitely while shipyards catch up. The Sentinel program underwent a congressionally mandated review in 2024 after its costs rose sharply, and GAO reported in 2025 that the program accounted for over $36 billion of a $49.3 billion cost increase across 30 major defense programs.
Budget arithmetic is the second constraint. A $946 billion ten-year estimate assumes programs stay on schedule; every delay pushes costs into later years and into competition with conventional modernization. The third factor is the treaty picture: with New START's limitation period ending February 5, 2026 and no successor agreed, the size and composition of the arsenal become questions settled by appropriations bills and posture reviews rather than negotiation.
Oversight, in other words, is the stabilizer. The CRS primer notes strong congressional interest in modernization oversight, and the annual budget cycle — justification documents, authorization marks, and appropriations conference — is where each leg's schedule and funding are actually decided, year by year. None of these pressures argues for abandoning the triad; they argue for reading its schedule commitments the way the record has earned: as plans subject to delay, priced in annual installments, and revised in public only after the slips have already happened.
