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| Nuclear weapons |
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| Background |
| Nuclear-armed states |
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Nuclear weapons delivery is the technology and systems used to place anuclear weapon at the position ofdetonation, on or near its target. All ninenuclear 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 thenuclear arms race.
Strategic nuclear weapons are intended primarily as part of a doctrine ofdeterrence by threatening large targets, such ascities ormilitary installations. These are generally delivered by some combination of land-basedintercontinental ballistic missiles, sea-basedsubmarine-launched ballistic missiles, and air-basedstrategic bombers carryinggravity bombs orcruise missiles. The possession of all three is known as anuclear 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, andnuclear depth charges, but they have become less salient since the end of theCold War.
Delivery systems were occasionally testedwith live warheads as a provocative form ofnuclear weapons testing andlive fire exercise.
Detection and interception of delivery vehicles is a key part of nuclear deterrence. For detection,early-warning radar andsatellite systems were developed. For interception,anti-ballistic missile andair defense systems were developed, some of which were themselves nuclear-armed. Warhead countermeasures developed against these includedecoys,multiple independently targetable reentrymaneuverable reentry vehicles and the use of high-altitude early detonations to cause radarnuclear blackout.
Since the end of the Cold War, nuclear weapons delivery has been advanced bystealth bombers andhypersonic weapons. According to the Council on Strategic Risks, 261 unique nuclear weapons systems have been developed by the fiveNPT-recognizednuclear-weapons states alone, with 47 in use by them as of 2025[update].[1]
Anuclear triad refers to astrategic nuclear arsenal which consists of three components, traditionallystrategic bombers,intercontinental ballistic missiles (ICBMs), andsubmarine-launched ballistic missiles (SLBMs). 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 afirst-strike attack; this, in turn, ensures a credible threat of asecond strike, and thus increases a nation'snuclear deterrence.[2][3][4]
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.Many countries formerly operated a wider range of strategic and especially tactical systems, especially during the Cold War. While most of these are no longer operational, Russia is the only country as of 2025 believed to operate nuclear-armedanti-ballistic missiles,surface-to-air missiles,anti-ship missilesanti-submarine weapons,depth bombs, andtorpedoes.[5]
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Historically the first method of nuclear weapons delivery, and the method used inthe twin instances ofnuclear warfare in history, was agravity bomb dropped by aplane. 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 thedecommissioningof nuclearmissiles, 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.[citation needed]
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 asin flight insertion (IFI) 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.[citation needed]
Various air-dropping techniques exist, includingtoss bombing,parachute-retarded delivery, andlaydown modes, intended to give the dropping aircraft time to escape the ensuing blast.[citation needed]
The earliest gravity nuclear bombs (Little Boy andFat Man) of the United States could only be carried, during the era of their creation, by the specialSilverplate limited production (65 airframes by 1947) version of theB-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 wingspanB-36 Peacemaker, the eight jet-enginedB-52 Stratofortress, and jet-powered British RAFV bombers, but by the mid-1950s smaller weapons had been developed that could be carried and deployed byfighter-bombers. Modern nuclear gravity bombs are so small that they can be carried by (relatively) smallmultirole fighter aircraft, such as the single-enginedF-16 andF-35.
Acruise missile is ajet- orrocket-propelledmissile thatflies aerodynamically at low altitude using an automated guidance system (usuallyinertial navigation, sometimes supplemented by eitherGPS ormid-course updates from friendly forces) to make them harder to detect or intercept. Cruise missiles can carry a nuclear warhead. They have a shorter range and smallerpayloads than ballistic missiles, so their warheads are smaller and less powerful.
TheAGM-86 ALCM is theUS Air Force's current nuclear-armedair-launched cruise missile. The ALCM is only carried on theB-52 Stratofortress which can carry 20 missiles. Thus the cruise missiles themselves can be compared with MIRV warheads. TheBGM/UGM-109 Tomahawksubmarine-launched cruise missile is capable of carrying nuclear warheads, but all nuclear warheads were removed following theIntermediate-Range Nuclear Forces Treaty.
Cruise missiles may also be launched frommobile 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:
However, cruise missiles are vulnerable to typicalair-defence means as they are essentiallyone-useunmanned aircraft; strategies such ascombat flights of fighter aircraft, or an integrated air-defence system comprising both CAP and ground-based elements, such assurface-air missiles (SAM), can be used to defend against a cruise missile attack.
Prior to the development of nuclear-armedsubmarine-launched ballistic missiles, the United States and the Soviet Union conducted their firstat-sea deterrence patrols using modifiedsubmarines armed with very large nuclear-armed cruise missiles; The US operated variousdiesel-electric submarines armed with theRegulus missile, and the Soviets operatedModifiedWhiskey-class armed with theP-5Пятёрка. 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- orGround-launched nuclear-armed cruise missiles (sometimes evennuclear-powered) wereconsideredbybothsides 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 nascentaeronautical androcketry technology of the time, especially when considering the temperamental and inefficient nature ofearly jet engines, which limited the range and use cases of strategic bombers and cruise missiles. Later on in the Cold War bothdisciplines had advanced far enough that it was feasible to create both reliable long-ranged cruise missiles and the strategic bombers able to launch them. Anotherarms-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, theSSC-X-9 "Skyfall" (9М730Буревестник) was revealed by Russian presidentVladimir Putin. It is under development and is slated to enter service sometime in the 2020s.
Missiles using aballistic trajectory deliver awarhead over the horizon; in the case of the most capable of these, classified asintercontinental ballistic missiles (ICBMs) (andsubmarine-launched ballistic missiles (SLBMs) if transported bysubmarine), they can reach distances of nearly tens of thousands of kilometers. Most ballistic missiles exit the Earth's atmosphere and re-enter it in theirsub-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 thelow Earth orbit has been banned by theOuter Space Treaty as early as 1967. Also, the eventual SovietFractional Orbital Bombardment System (FOBS) 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 theSALT II treaty.
An ICBM is more than 20 times as fast as abomber and more than 10 times as fast as afighter plane, and also flying at a much higher altitude[clarification needed], and therefore more difficult to defend against. ICBMs can also befired quickly in the event of a surprise attack.
Early ballistic missiles carried a singlewarhead, often ofmegaton-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 ininertial guidance systems. This set the stage for smaller warheads in the hundreds-of-kilotons-range yield, and consequently for ICBMs havingmultiple independently targetable reentry vehicles (MIRV). 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 makesanti-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 samephysics 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.[15]
While thefirst 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 SovietR-7.
The firstSLBM-carrying submarine was also Soviet; theprototype ModifiedZulu-class and the mass-producedGolf-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; theGeorge Washington-class, which launched thePolaris SLBM. The subsequent arms-race culminated in some of the largest submarines ever designed; theTrident-armed 170-meter longOhio-class submarine armed with 24 × 8 MIRVTrident missiles, and thebattlecruiser-sized 48,000tonneProject941Акула, theTyphoon-class submarine, armed with 20R-39s with 10 MIRVs each. After the Cold War, SSBN and subsequently SLBM development have slowed, but nascent nuclear powers are buildingnovel classes ofSSB(N)s, while the established powers, all members of theUnited Nations Security Council, are plotting thenext-generationofnuclear-powerednuclear-armed ballistic missile submarines.
Hypersonically-GlidingWarheads are a novel form of warhead to arm ballistic missiles. These maneuverable devices threaten to obsolate current forms ofABM defences, thus various nascent and established nuclear powers areracing tofieldexamplesof suchsystems.
Other delivery methods includednuclear artillery shells,mines such as theMedium Atomic Demolition Munition and the novelBlue Peacock,nuclear depth bombs, andnuclear torpedoes. An'Atomic Bazooka' was also fielded, designed to be used against large formations of tanks.
In the 1950s the US developed small nuclear warheads for air defense use, such as theNike Hercules. From the 1950s to the 1980s, the United States and Canada fielded alow-yield nuclear armedair-to-air rocket, theAIR-2 Genie. Further developments of this concept, some with much larger warheads, led to the earlyanti-ballistic missiles. The United States have largely taken nuclear air-defense weapons out of service with the fall of theSoviet Union in the early 1990s. Russia updated its nuclear armed Soviet era anti-ballistic missile (ABM) system, known as theA-135 anti-ballistic missile system in 1995. It is believed that the, in development successor to the nuclear A-135, theA-235 Samolet-M, will dispense with nuclear interception warheads and instead rely on a conventionalhit-to-kill capability to destroy its target.[16]
Small, two-man portable tactical weapons (erroneously referred to assuitcase bombs), such as theSpecial Atomic Demolition Munition, have been developed, although the difficulty to combine sufficient yield with portability limits their military utility.
According to an audit by theBrookings Institution, between 1940 and 1996, the US spent $11.7 trillion in present-day terms[17] on nuclear weapons programs. 57 percent of which was spent on buildingdelivery mechanisms for nuclear weapons. 6.3 percent of the total, $732 billion in present-day terms, was spent on weaponnuclear waste management, for example, cleaning up theHanford site with environmentalremediation, and 7 percent of the total, $820 billion was spent on the manufacturing of nuclear weapons themselves.[18]
Strictly speaking however not all this 57 percent was spent solely on "weapons programs" delivery systems.
For example, two suchdelivery mechanisms, theAtlas ICBM andTitan II, were re-purposed as humanlaunch vehicles forhuman spaceflight, both were used in the civilianProject Mercury andProject Gemini programs respectively, which are regarded as stepping stones in the evolution of US human spaceflight.[19][20] The Atlas vehicle sentJohn Glenn, the first American into orbit. Similarly in theSoviet Union it was theR-7 ICBM/launch vehicle that placed the first artificial satellite in space,Sputnik, on 4 October 1957, and the firsthuman spaceflight in history was accomplished on a derivative of the R-7, theVostok, onApril 12, 1961, bycosmonautYuri Gagarin. A modernized version of the R-7 is still in use as thelaunch vehicle for the Russian Federation, in the form of theSoyuz spacecraft. TheProton rocket family was originally developed as a "super-heavy ICBM" to launch heavy warheads with a 100 megaton yield of the same design used in the 1961Tsar Bomba test.
The first trueweather satellite, theTIROS-1 was launched on theThor-Able launch vehicle in April 1960.[21] ThePGM-17 Thor was the first operationalIRBM (intermediate ballistic missile) deployed by the US Air Force (USAF). TheSoviet Union's first fully operational weather satellite, theMeteor 1 was launched on 26 March 1969, on theVostok rocket,[citation needed] a derivative of theR-7 ICBM.
WD-40 was first used byConvair to protect the outer skin, and more importantly, the paper thin "balloon tanks" of theAtlas missile from rust and corrosion.[22][23] These stainless steel fuel tanks were so thin that, when empty, they had to be kept inflated with nitrogen gas to prevent their collapse.
In 1953, Dr.S. Donald Stookey of the Corning Research and Development Division inventedPyroceram, a whiteglass-ceramic material capable of withstanding a thermal shock (sudden temperature change) of up to 450 °C (840 °F). It evolved from materials originally developed for a USballistic missile program, and Stookey's research involved heat-resistant material fornose cones.[24]
Precise navigation would enable United Statessubmarines to get an accurate fix of their positions before they launched their SLBMs, this spurred development of triangulation methods that ultimately culminated inGPS.[25] The motivation for having accurate launch position fixes, and missile velocities,[26] is twofold. It results in a tighter target impactcircular error probable and therefore by extension, reduces the need for the earlier generation of heavy multi-megaton nuclear warheads, such as theW53 to ensure the target is destroyed. With increased target accuracy,a greater number of lighter, multi-kiloton range warheads can bepacked on a given missile, giving a higher number of separate targets that can be hit per missile.
During a Labor Day weekend in 1973, a meeting of about twelve military officers at the Pentagon discussed the creation of aDefense Navigation Satellite System (DNSS). It was at this meeting that "the real synthesis that became GPS was created." Later that year, the DNSS program was namedNavstar, or Navigation System Using Timing and Ranging.[27]
During the development of the submarine-launchedPolaris missile, a requirement to accurately know the submarine's location was needed to ensure a highcircular error probable warhead target accuracy. This led the US to develop theTransit system.[28] In 1959, ARPA (renamedDARPA in 1972) also played a role in Transit.[29][30][31]
The first satellite navigation system,Transit, used by theUnited States Navy, was first successfully tested in 1960. It used a constellation of five satellites and could provide a navigational fix approximately once per hour. In 1967, the US Navy developed theTimation satellite that proved the ability to place accurate clocks in space, a technology required by the latterGlobal Positioning System. In the 1970s, the ground-basedOmega Navigation System, based on phase comparison of signal transmission from pairs of stations,[35] became the first worldwide radio navigation system. Limitations of these systems drove the need for a more universal navigation solution with greater accuracy.
While there were wide needs for accurate navigation in military and civilian sectors, almost none of those was seen as justification for the billions of dollars it would cost in research, development, deployment, and operation for a constellation of navigation satellites. During theCold Wararms race, the nuclear threat to the existence of the United States was the one need that did justify this cost in the view of the United States Congress. This deterrent effect is why GPS was funded. Thenuclear triad consisted of the United States Navy'ssubmarine-launched ballistic missiles (SLBMs) along withUnited States Air Force (USAF) strategic bombers andintercontinental ballistic missiles (ICBMs). Considered vital to the nuclear-deterrence posture, accurate determination of the SLBM launch position was aforce multiplier.
Precise navigation would enable United Statessubmarines to get an accurate fix of their positions before they launched their SLBMs.[25] The USAF, with two-thirds of the nuclear triad, also had requirements for a more accurate and reliable navigation system. The Navy and Air Force were developing their own technologies in parallel to solve what was essentially the same problem. To increase the survivability of ICBMs, there was a proposal to use mobile launch platforms (such as RussianSS-24 andSS-25) and so the need to fix the launch position had similarity to the SLBM situation.
In 1960, the Air Force proposed a radio-navigation system called MOSAIC (MObile System for Accurate ICBM Control) that was essentially a 3-D LORAN. A follow-on study, Project 57, was worked in 1963 and it was "in this study that the GPS concept was born". That same year, the concept was pursued as Project 621B, which had "many of the attributes that you now see in GPS"[36] and promised increased accuracy for Air Force bombers as well as ICBMs. Updates from the Navy Transit system were too slow for the high speeds of Air Force operation. The Navy Research Laboratory continued advancements with their Timation (Time Navigation) satellites, first launched in 1967, and with the third one in 1974 carrying the first atomic clock into orbit.[37]
Another important predecessor to GPS came from a different branch of the United States military. In 1964, theUnited States Army orbited its first Sequential Collation of Range (SECOR) satellite used for geodetic surveying. The SECOR system included three ground-based transmitters from known locations that would send signals to the satellite transponder in orbit. A fourth ground-based station, at an undetermined position, could then use those signals to fix its location precisely. The last SECOR satellite was launched in 1969.[38] Decades later, during the early years of GPS, civilian surveying became one of the first fields to make use of the new technology, because surveyors could reap benefits of signals from the less-than-complete GPS constellation years before it was declared operational. GPS can be thought of as an evolution of the SECOR system where the ground-based transmitters have been migrated into orbit.[citation needed]
The Titan II ICBM was converted into the Titan/Gemini space launch vehicle (SLV) by man-rating critical systems. It served as a significant stepping stone in the evolution of the US human spaceflight program using expendable launch vehicles, culminating in the Apollo program. Twelve successful Gemini launches occurred between April 1964 and November 1966.
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