Editing Multiple independently targetable reentry vehicle (section)

== Purpose ==
The military purpose of a MIRV is fourfold:
*Enhance [[first-strike]] proficiency for strategic forces.<ref name="gwu.edu">{{cite web |url= https://nsarchive2.gwu.edu//nsa/NC/mirv/mirv.html |title= MIRV: A BRIEF HISTORY OF MINUTEMAN and MULTIPLE REENTRY VEHICLES |last= Buchonnet |first= Daniel |date= 1976-02-01 |website= gwu.edu |publisher= [[Lawrence Livermore National Laboratory|Lawrence Livermore Laboratory]] |agency= [[United States Department of Defense]] |language= en |archive-url= https://web.archive.org/web/20190915054553/https://nsarchive2.gwu.edu//nsa/NC/mirv/mirv.html |archive-date= 2019-09-15 |url-status= live |access-date= 2019-11-24 |quote= The idea of multiple warheads dates back to the mid-1960s, but the key year in the history of the MIRV concept was 1962 when several of technological developments made it possible for scientists and engineers to conceive of multiple, separately targeted warheads that could hit a growing list of Soviet nuclear threat targets. One important innovation was that the weapons laboratories had designed small thermonuclear weapons, a necessary condition for deploying multiple reentry vehicles on the relatively small Minuteman. |ref= gwu.edu |df= dmy-all}}</ref>
*Providing greater target damage for a given [[thermonuclear weapon]] payload. Several small and lower yield warheads cause much more target damage area than a single warhead alone. This, in turn, reduces the number of missiles and launch facilities required for a given destruction level&nbsp;&ndash; much the same as the purpose of a [[cluster munition]].<ref name="Hansen">The best overall printed sources on nuclear weapons design are: [[Chuck Hansen|Hansen, Chuck]]. ''U.S. Nuclear Weapons: The Secret History.'' San Antonio, TX: Aerofax, 1988; and the more-updated Hansen, Chuck, "[http://www.uscoldwar.com/ Swords of Armageddon: U.S. Nuclear Weapons Development since 1945] {{Webarchive|url=https://web.archive.org/web/20161230020259/http://www.uscoldwar.com/ |date=2016-12-30 }}" (CD-ROM & download available). PDF. 2,600 pages, Sunnyvale, California, Chukelea Publications, 1995, 2007. {{ISBN|978-0-9791915-0-3}} (2nd Ed.)</ref>
*With single-warhead missiles, one missile must be launched for each target. By contrast, with a MIRV warhead, the post-boost (or bus) stage can dispense the warheads against multiple targets across a broad area.
*Reduces the effectiveness of an [[anti-ballistic missile]] system that relies on intercepting individual warheads.<ref name="Aldridge1983">{{cite book|author=Robert C. Aldridge|title=First Strike!: The Pentagon's Strategy for Nuclear War|url=https://books.google.com/books?id=Pb0mnwEACAAJ|access-date=26 February 2013|year=1983|publisher=South End Press|isbn=978-0-89608-154-3|pages=65–|archive-url=https://web.archive.org/web/20140716180535/http://books.google.com/books/about/First_Strike.html?id=Pb0mnwEACAAJ|archive-date=16 July 2014|url-status=live}}</ref> While a MIRV attacking missile can have multiple warheads (3{{hyphen}}12 on United States and Russian missiles), interceptors may have only one warhead per missile. Thus, in both a military and an economic sense, MIRVs render ABM systems less effective, as the costs of maintaining a workable defense against MIRVs would greatly increase, requiring multiple defensive missiles for each offensive one. Decoy [[Atmospheric entry|re-entry]] vehicles can be used alongside actual warheads to minimize the chances of the actual warheads being intercepted before they reach their targets. A system that destroys the missile earlier in its trajectory (before MIRV separation) is not affected by this but is more difficult, and thus more expensive to implement.

MIRV land-based [[Intercontinental ballistic missile|ICBM]]s were considered destabilizing because they tended to put a premium on [[first-strike|striking first]].<ref>{{Cite web |url=https://www.rand.org/pubs/research_reports/RR1628.html |title=China's Evolving Nuclear Deterrent: Major Drivers and Issues for the United States |date=15 March 2017 |access-date=2017-12-01 |archive-url=https://web.archive.org/web/20171201182213/https://www.rand.org/pubs/research_reports/RR1628.html |archive-date=2017-12-01 |url-status=live |last1=Heginbotham |first1=Eric }}</ref> The world's first MIRV—US [[Minuteman III]] missile of 1970—threatened to rapidly increase the US's deployable nuclear arsenal and thus the possibility that it would have enough bombs to destroy virtually all of the [[Russia and weapons of mass destruction|Soviet Union's nuclear weapons]] and negate any significant retaliation. Later on the US feared the Soviet's MIRVs because Soviet missiles had a greater [[throw-weight]] and could thus put more warheads on each missile than the US could. For example, the US MIRVs might have increased their warhead per missile count by a factor of 6 while the Soviets increased theirs by a factor of 10. Furthermore, the US had a much smaller proportion of its nuclear arsenal in ICBMs than the Soviets. Bombers could not be outfitted with MIRVs so their capacity would not be multiplied. Thus the US did not seem to have as much potential for MIRV usage as the Soviets. However, the US had a larger number of [[submarine-launched ballistic missile]]s, which could be outfitted with MIRVs, and helped offset the ICBM disadvantage. It is because of their first-strike capability that land-based MIRVs were banned under the [[START II]] agreement. START II was ratified by the [[Russian Duma]] on 14 April 2000, but Russia withdrew from the treaty in 2002 after the US withdrew from the [[Anti-Ballistic Missile Treaty|ABM treaty]].