Nuclear weapons delivery
Nuclear weapons delivery is the technology and systems used to place a nuclear weapon at the position of detonation, on or near its target. All nine nuclear states have developed some form of medium- to long-range delivery system for their nuclear weapons. Alongside improvement of weapons, their development and deployment played a key role in the nuclear arms race.
Strategic nuclear weapons are intended primarily as part of a doctrine of deterrence by threatening large targets, such as cities or military installations. These are generally delivered by some combination of land-based intercontinental ballistic missiles, sea-based submarine-launched ballistic missiles, and air-based strategic bombers carrying gravity bombs or cruise missiles. The possession of all three is known as a nuclear triad.
Tactical nuclear weapons are intended for battlefield usage and/or destroying specific military, communications, or infrastructure targets, and generally have lower yields. Delivery systems developed for them include shorter-range ground-, air-, and sea-launched missiles, nuclear artillery, nuclear land mines, nuclear torpedoes, and nuclear depth charges, but they have become less salient since the end of the Cold War.
Delivery systems were occasionally tested with live warheads as a provocative form of nuclear weapons testing and live fire exercise.
Detection and interception of delivery vehicles is a key part of nuclear deterrence. For detection, early-warning radar and satellite systems were developed. For interception, anti-ballistic missile and air defense systems were developed, some of which were themselves nuclear-armed. Warhead countermeasures developed against these include decoys, multiple independently targetable reentry maneuverable reentry vehicles and the use of high-altitude early detonations to cause radar nuclear blackout.
Since the end of the Cold War, nuclear weapons delivery has been advanced by stealth bombers and hypersonic weapons. According to the Council on Strategic Risks, 261 unique nuclear weapons systems have been developed by the five NPT-recognized nuclear-weapons states alone, with 47 in use by them as of 2025.
Nuclear triad
A nuclear triad refers to a strategic nuclear arsenal which consists of three components, traditionally strategic bombers, intercontinental ballistic missiles, and submarine-launched ballistic missiles. The purpose of having a three-branched nuclear capability is to significantly reduce the possibility that an enemy could destroy all of a nation's nuclear forces in a first-strike attack; this, in turn, ensures a credible threat of a second strike, and thus increases a nation's nuclear deterrence.Country comparison
The table uses the following identifiers:- — This country has a nuclear mission assigned to this delivery system.
- — This country does not have a nuclear mission assigned to this delivery system.
- — It is unclear if this country has a nuclear mission assigned to this delivery system.
- — This country is developing this delivery system with a nuclear mission envisioned.
Main delivery mechanisms
Gravity bomb
Historically the first method of nuclear weapons delivery, and the method used in the twin instances of nuclear warfare in history, was a gravity bomb dropped by a plane. In the years leading up to the development and deployment of nuclear-armed missiles, nuclear bombs represented the most practical means of nuclear weapons delivery; even today, and especially with the decommissioning of nuclear missiles, aerial bombing remains the primary means of offensive nuclear weapons delivery, and the majority of US nuclear warheads are represented in bombs, although some are in the form of missiles.Gravity bombs are designed to be dropped from planes, which requires that the weapon be able to withstand vibrations and changes in air temperature and pressure during the course of a flight. Early weapons often had a removable core for safety, known as in flight insertion cores, being inserted or assembled by the air crew during flight. They had to meet safety conditions, to prevent accidental detonation or dropping. A variety of types also had to have a fuse to initiate detonation. US nuclear weapons that met these criteria are designated by the letter "B" followed, without a hyphen, by the sequential number of the "physics package" it contains. The "B61", for example, was the primary bomb in the US arsenal for decades.
Various air-dropping techniques exist, including toss bombing, parachute-retarded delivery, and laydown modes, intended to give the dropping aircraft time to escape the ensuing blast.
The earliest gravity nuclear bombs of the United States could only be carried, during the era of their creation, by the special Silverplate limited production version of the B-29 Superfortress. The next generation of weapons were still so big and heavy that they could only be carried by bombers such as the six/ten-engined, seventy-meter wingspan B-36 Peacemaker, the eight jet-engined B-52 Stratofortress, and jet-powered British RAF V bombers, but by the mid-1950s smaller weapons had been developed that could be carried and deployed by fighter-bombers. Modern nuclear gravity bombs are so small that they can be carried by small multirole fighter aircraft, such as the single-engined F-16 and F-35.
Cruise missile
A cruise missile is a jet- or rocket-propelled missile that flies aerodynamically at low altitude using an automated guidance system to make them harder to detect or intercept. Cruise missiles can carry a nuclear warhead. They have a shorter range and smaller payloads than ballistic missiles, so their warheads are smaller and less powerful.The AGM-86 ALCM is the US Air Force's current nuclear-armed air-launched cruise missile. The ALCM is only carried on the B-52 Stratofortress which can carry 20 missiles. Thus the cruise missiles themselves can be compared with MIRV warheads. The BGM/UGM-109 Tomahawk submarine-launched cruise missile is capable of carrying nuclear warheads, but all nuclear warheads were removed following the Intermediate-Range Nuclear Forces Treaty.
Cruise missiles may also be launched from mobile launchers on the ground, and from naval ships.
There is no letter change in the US arsenal to distinguish the warheads of cruise missiles from those for ballistic missiles.
Cruise missiles, even with their lower payload, speed, and thus readiness, have a number of advantages over ballistic missiles for the purposes of delivering nuclear strikes:
- Launch of a cruise missile is difficult to detect early from satellites and other long-range means, contributing to a surprise factor of attack.
- That, coupled with the ability to actively maneuver in flight, allows for penetration of strategic anti-missile systems aimed at intercepting ballistic missiles, which typically fly on a ballistic arc without complex maneuvers.
Prior to the development of nuclear-armed submarine-launched ballistic missiles, the United States and the Soviet Union conducted their first at-sea deterrence patrols using modified submarines armed with very large nuclear-armed cruise missiles; The US operated various diesel-electric submarines armed with the Regulus missile, and the Soviets operated Modified Whiskey-class armed with the P-5 Пятёрка. These early nuclear-armed SSGs served for a few decades until there were enough SSBNs put in service, after which they were retired. Their spiritual successors, armed with larger amounts of more modern, smaller cruise missiles continue to serve to this day serving in a tactical strike role, although they could be rearmed with nuclear cruise-missiles if need be.
Air- or ground-launched nuclear-armed cruise missiles were considered by both sides early in the Cold War, but both concluded that it was impractical with the technology of the time. Nuclear-powered aircraft were considered due to the nascent aeronautical and rocketry technology of the time, especially when considering the temperamental and inefficient nature of early jet engines, which limited the range and use cases of strategic bombers and cruise missiles. Later on in the Cold War both disciplines had advanced far enough that it was feasible to create both reliable long-ranged cruise missiles and the strategic bombers able to launch them. Another arms-race began which produced contemporary post-Cold War cruise missiles and launch systems; VLS technology also allowed for surface ships to be armed with nuclear-armed cruise missiles while concealing their true payload. In 2018, the first operational nuclear-powered strategic cruise missile, the SSC-X-9 "Skyfall" was revealed by Russian president Vladimir Putin. It is under development and is slated to enter service sometime in the 2020s.
Ballistic missile
s using a ballistic trajectory deliver a warhead over the horizon; in the case of the most capable of these, classified as intercontinental ballistic missiles , they can reach distances of nearly tens of thousands of kilometers. Most ballistic missiles exit the Earth's atmosphere and re-enter it in their sub-orbital spaceflight. Ballistic missiles aren't always nuclear armed, but the conspicuous and alarming nature of their launch often precludes arming ICBMs and SLBMs, the most capable classes of ballistic missiles, with conventional warheads.Placement of nuclear missiles on the low Earth orbit has been banned by the Outer Space Treaty as early as 1967. Also, the eventual Soviet Fractional Orbital Bombardment System that served a similar purpose—it was just deliberately designed to deorbit before completing a full circle—was phased out in January 1983 in compliance with the SALT II treaty.
An ICBM is more than 20 times as fast as a bomber and more than 10 times as fast as a fighter plane, and also flying at a much higher altitude, and therefore more difficult to defend against. ICBMs can also be fired quickly in the event of a surprise attack.
Early ballistic missiles carried a single warhead, often of megaton-range yield. Because of the limited accuracy of the missiles, this kind of high yield was considered necessary to ensure a particular target's destruction. Since the 1970s modern ballistic weapons have seen the development of far more accurate targeting technologies, particularly due to improvements in inertial guidance systems. This set the stage for smaller warheads in the hundreds-of-kilotons-range yield, and consequently for ICBMs having multiple independently targetable reentry vehicles. Advances in technology have enabled a single missile to launch a payload containing several warheads; the number of which depended on the missile's and payload bus' design. MIRVs has a number of advantages over a missile with a single warhead. With few additional costs, it allows a single missile to strike multiple targets, or to inflict maximum damage on a single target by attacking it with multiple warheads. It makes anti-ballistic missile defense even more difficult, and even less economically viable, than before.
Missile warheads in the American arsenal are indicated by the letter "W"; for example, the W61 missile warhead would have the same physics package as the B61 gravity bomb described above, but it would have different environmental requirements, and different safety requirements since it would not be crew-tended after launch and remain atop a missile for a great length of time.
While the first modern ballistic missile designed is the basis of contemporary rocket- and missilery, it never carried a nuclear warhead. The first ICBM ever designed was the Soviet R-7.
The first SLBM-carrying submarine was also Soviet; the prototype Modified Zulu-class and the mass-produced Golf-class ballistic missile submarines carried their SLBMs in their sails, but these pioneering designs had to surface to launch their ballistic missiles. The Americans responded with the first "modern design" of ballistic missile subs; the George Washington-class, which launched the Polaris SLBM. The subsequent arms-race culminated in some of the largest submarines ever designed; the Trident-armed 170-meter long Ohio-class submarine armed with 24 × 8 MIRV Trident missiles, and the battlecruiser-sized 48,000 tonne Project 941 Акула, the Typhoon-class submarine, armed with 20 R-39s with 10 MIRVs each. After the Cold War, SSBN and subsequently SLBM development have slowed, but nascent nuclear powers are building novel classes of SSBs, while the established powers, all members of the United Nations Security Council, are plotting the next-generation of nuclear-powered nuclear-armed ballistic missile submarines.
Hypersonically-Gliding Warheads are a novel form of warhead to arm ballistic missiles. These maneuverable devices threaten to obsolate current forms of ABM defences, thus various nascent and established nuclear powers are racing to field examples of such systems.