Editing Nuclear weapon (section)

== Weapons delivery ==
{{See also|Nuclear weapons delivery|Nuclear triad|Strategic bomber|Intercontinental ballistic missile|Submarine-launched ballistic missile}}
[[File:Fat Man (replica of nuclear bomb).jpg|right|thumb|The first nuclear weapons were [[gravity bomb]]s, such as this "[[Fat Man]]" weapon dropped on [[Nagasaki, Nagasaki|Nagasaki]], Japan. They were large and could only be delivered by [[heavy bomber]] aircraft]]
[[File:Dnepr rocket lift-off 1.jpg|left|thumb|upright|A demilitarized, [[Dnepr (rocket)|commercial launch]] of the Russian [[Strategic Rocket Forces]] R-36 [[ICBM]]; also known by the NATO reporting name: [[SS-18 Satan]]. Upon its first fielding in the late 1960s, the SS-18 remains the single highest [[throw weight]] missile delivery system ever built.]]

The system used to [[Nuclear weapons delivery|deliver]] a nuclear weapon to its target is an important factor affecting both [[nuclear weapon design]] and [[nuclear warfare|nuclear strategy]]. The design, development, and maintenance of delivery systems are among the most expensive parts of a nuclear weapons program; they account, for example, for 57% of the financial resources spent by the United States on nuclear weapons projects since 1940.<ref>Stephen I. Schwartz, ed., ''Atomic Audit: The Costs and Consequences of U.S. Nuclear Weapons Since 1940.'' Washington, D.C.: Brookings Institution Press, 1998. See also [http://www.brook.edu/fp/projects/nucwcost/figure1.htm Estimated Minimum Incurred Costs of U.S. Nuclear Weapons Programs, 1940–1996], an excerpt from the book. {{webarchive |url=https://web.archive.org/web/20081121144318/http://www.brook.edu/fp/projects/nucwcost/figure1.htm |date=November 21, 2008}}</ref>

The simplest method for delivering a nuclear weapon is a [[gravity bomb]] dropped from [[aircraft]]; this was the method used by the [[Atomic bombings of Hiroshima and Nagasaki|United States against Japan]] in 1945. This method places few restrictions on the size of the weapon. It does, however, limit attack range, response time to an impending attack, and the number of weapons that a country can field at the same time. With miniaturization, nuclear bombs can be delivered by both [[strategic bomber]]s and tactical [[fighter-bomber]]s. This method is the primary means of nuclear weapons delivery; the majority of US nuclear warheads, for example, are free-fall gravity bombs, namely the [[B61 nuclear bomb|B61]], which is being improved upon to this day.<ref name="Hansen" /><ref>{{Cite web |last=Mehta |first=Aaron |date=2023-10-27 |title=US to introduce new nuclear gravity bomb design: B61-13 |url=https://breakingdefense.sites.breakingmedia.com/2023/10/us-to-introduce-new-nuclear-gravity-bomb-design-b61-13/ |access-date=2023-11-27 |website=Breaking Defense |language=en-US |archive-date=December 17, 2023 |archive-url=https://web.archive.org/web/20231217083734/https://breakingdefense.com/2023/10/us-to-introduce-new-nuclear-gravity-bomb-design-b61-13/ |url-status=live }}</ref>

[[File:Trident C-4 montage.jpg|thumb|right|Montage of an inert test of a United States [[Trident missile|Trident]] [[SLBM]] (submarine launched ballistic missile), from submerged to the [[Missile defense#Terminal phase|terminal]], or re-entry phase, of the [[multiple independently targetable reentry vehicle]]s]]

Preferable from a strategic point of view is a nuclear weapon mounted on a [[missile]], which can use a [[Ballistics|ballistic]] trajectory to deliver the warhead over the horizon. Although even short-range missiles allow for a faster and less vulnerable attack, the development of long-range [[intercontinental ballistic missile]]s (ICBMs) and [[submarine-launched ballistic missile]]s (SLBMs) has given some nations the ability to plausibly deliver missiles anywhere on the globe with a high likelihood of success.

More advanced systems, such as [[multiple independently targetable reentry vehicle]]s (MIRVs), can launch multiple warheads at different targets from one missile, reducing the chance of a successful [[missile defense]]. Today, missiles are most common among systems designed for delivery of nuclear weapons. Making a warhead small enough to fit onto a missile, though, can be difficult.<ref name="Hansen" />

[[Tactical nuclear weapon|Tactical weapons]] have involved the most variety of delivery types, including not only gravity bombs and missiles but also [[nuclear artillery|artillery]] shells, [[atomic demolition munition|land mines]], and [[nuclear depth charge]]s and [[nuclear torpedo|torpedoes]] for [[anti-submarine warfare]]. An atomic [[mortar (weapon)|mortar]] has been tested by the United States. Small, two-man portable tactical weapons (somewhat misleadingly referred to as [[suitcase bomb]]s), such as the [[Special Atomic Demolition Munition]], have been developed, although the difficulty of combining sufficient yield with portability limits their military utility.<ref name="Hansen" />