A B-52 lifts off from Minot in North Dakota, a Minuteman III sits in a silo somewhere under the Great Plains, and an Ohio-class submarine cruises silently at an undisclosed point in the ocean. Together they form the United States nuclear triad: three completely different ways of delivering a nuclear weapon, maintained side by side since the early 1960s.

Why build three systems to do one job? The short answer is survival. The long answer says a lot about deterrence, about crisis signalling, and about why the oldest leg of the triad, the bomber, is still the one politicians reach for first when they want to send a message.

Why three legs instead of one

The triad did not begin as a grand design. According to the Congressional Research Service, the United States first built three kinds of nuclear delivery systems largely because each military service wanted a role in the nuclear arsenal. The Air Force had bombers and land-based missiles, the Navy had submarines. The strategic logic came afterwards.

That logic is simple. If all of a country’s nuclear weapons sat in one kind of system, an enemy could hope to destroy them in a surprise first strike, or a single technical failure could ground them all. Spread the weapons across air, land and sea, each with different strengths and weaknesses, and no attacker can be confident of disarming you. That is what makes a first strike unattractive in the first place.

The “aha” is that the three legs are not meant to be equally good at everything. Each covers the others’ weak spots. US defence planners also value the triad as a hedge: if one leg suffers an unexpected technical problem, weight can be shifted to the other two.

The bomber leg: slow, visible and recallable

Bombers are the slowest leg. A missile reaches its target in minutes; a bomber takes hours. On the ground, a parked bomber is the most vulnerable target in the whole arsenal. So why keep them? Because those same hours are a feature, not a bug.

A bomber can be launched to save it from attack, dispersed, and then called back if the crisis cools. CRS notes that heavy bombers could be dispersed quickly and launched to enhance their survivability, and recalled to their bases if a crisis did not escalate into conflict. No missile can be un-launched. A bomber can turn around.

That visibility is the bomber’s other unique gift. When the United States wants to reassure allies or warn an adversary, it sends B-52s or B-2s on long-range flights, flyovers and deployments that everyone can see. Missiles in silos and submarines at sea deter precisely because they are hidden; bombers deter partly because they are shown. They also carry conventional weapons, so the same aircraft can fight a non-nuclear war.

Today the bomber leg is made up of two types. The Air Force has 20 B-2 Spirit stealth bombers based in Missouri, which carry nuclear gravity bombs but not cruise missiles, and 74 B-52H bombers in Louisiana and North Dakota, which carry nuclear air-launched cruise missiles. Not every B-52 is nuclear-capable: some have been converted to conventional-only roles.

The future is the B-21 Raider, a stealth bomber for both conventional and nuclear missions. It is in testing and initial production, and the Air Force plans to buy at least 100. The B-52 will soldier on alongside it, armed with the new AGM-181 Long-Range Standoff cruise missile once it is ready.

The Wall Street Journal compares US and Chinese nuclear missiles, submarines and stealth bombers leg by leg.

The land leg: ICBMs and promptness

The second leg lives underground. The Air Force deploys 400 Minuteman III intercontinental ballistic missiles in silos in Wyoming, Montana and North Dakota, while keeping all 450 silo launchers. Each missile originally carried three warheads but now carries one, a change made to meet New START treaty limits.

ICBMs bring promptness. They can be launched faster than the other legs and reach their targets sooner, and firing one is an unmistakable act. CRS describes how ICBMs eventually had the accuracy and prompt responsiveness needed to attack hardened targets. Because there are hundreds of silos, an enemy would need to commit a huge number of its own warheads to destroy them.

Minuteman III is old, first deployed in the 1970s, and its replacement is the LGM-35A Sentinel, which the Air Force plans to buy in a run of 659 missiles for testing and deployment. In 2024 the Pentagon ran a congressionally mandated review of the programme because of cost overruns and delays.

Air Force Global Strike Command footage of two unarmed Minuteman III test launches in one week.

The sea leg: the one nobody can find

The third leg is the most survivable. The US Navy operates 14 Ohio-class ballistic missile submarines from bases in Washington state and Georgia, each now carrying 20 Trident II D5 missiles instead of the original 24. On patrol, deep in the ocean, they are extremely hard to locate. Their job is to guarantee that, whatever happens to the bombers and silos, a retaliatory strike remains possible.

The Navy is buying 12 Columbia-class submarines with 16 missile tubes each to replace them. The lead boat was due to begin patrols in fiscal year 2031, but the Navy has said it is delayed. Air power plays a supporting role at sea too: US Air Force aircraft have flown armed escort exercises with surfaced ballistic missile submarines leaving port.

Who else has a triad

Only a handful of countries operate all three legs. Russia keeps a full triad of ICBMs, ballistic missile submarines and Tu-95MS Und Tu-160 bombers. India completed its triad in November 2018, when the submarine INS Arihant finished its first deterrence patrol, joining land-based missiles and nuclear-capable aircraft of the Indische Luftwaffe.

China is usually described as having a triad as well, with land-based missiles, Jin-class submarines and the nuclear-capable H-6N bomber. The Federation of American Scientists, however, calls China’s air leg nascent, consisting of a single brigade still developing tactics and procedures for the nuclear mission.

The two European nuclear powers do not have triads. The United Kingdom relies on continuous at-sea deterrence: one Trident submarine on patrol at all times. In June 2025 London announced it would buy at least 12 F-35A fighters to join NATO’s dual-capable aircraft nuclear mission, reintroducing a nuclear role for the Royal Air Force, but those jets would carry US B61-12 bombs under NATO arrangements, not a sovereign British weapon. France runs a dyad of ballistic missile submarines and nuclear-capable Rafale aircraft armed with the ASMP-A cruise missile, having given up its land-based missiles in the 1990s.

A Trident II D5LE missile launched from the Ohio-class submarine USS Wyoming during a demonstration and shakedown operation.

The price of keeping all three

Three legs are expensive. In 2025 the Congressional Budget Office estimated that US plans to operate and modernise nuclear forces would cost $946 billion over ten years, and every leg is being replaced at once: B-21 for the B-2, Sentinel for Minuteman III, Columbia for Ohio. The New START treaty, which capped US and Russian deployed strategic warheads, expired on 5 February 2026.

The argument for paying it has barely changed since the 1960s. A submarine you cannot find, a missile you cannot stop and a bomber you can see, and call back. Each answers a different question, and together they leave an adversary with none worth asking.

Sources: Congressional Research Service (IF10519, April 2026; RL33640), US Department of Defense Nuclear Posture Reviews 2010 and 2022, UK Government (GOV.UK), Arms Control Association, Federation of American Scientists, SIPRI Yearbook

Header photo: U.S. Air Force photo / Senior Airman Brittany Y. Auld / Wikimedia Commons, public domain