Declassified U.S. Nuclear Weapon Stockpile Numbers 1945 - 2015
Das Nuklearwaffenpotential der USA in Zahlen 1945 - 2015

1 Definitions

”Builds numbers reported are total annual quantities for fully retired weapon systems in 1995. This represents a subset of United States nuclear weapon production. The annual production of nuclear weapons still in the stockpile remain classified and thus is excluded.
Retirement rates from 1984 to 1989 are adjusted from the stockpile memorandum retirement numbers to better reflect the number of weapons truly retired. Retirement numbers reported below reflect weapons retired for conversions, modifications, or disassemblies for disposal. Retirement numbers depend critically on how the term retirement is defined.
Disassemblies reported below reflect only the number of weapons dismantled for actual disposal. It should be noted that raw disassembly numbers published elsewhere by the Department are typically larger reflecting the number of times a weapon is disassembled but not necessarily disassembled for disposal or dismantlement purposes. An example of this would be for repair, a weapon might be disassembled to replace a part and then returned to the stockpile. Records prior to 1980 on disassemblies for disposal are not immediately available but will be provided in the future if possible.”

Sources / Quellen:
Department of Energy, Declassification of Certain Characteristics of the United States Nuclear Weapon Stockpile, 1994. online: https://www.osti.gov/opennet/forms.jsp?formurl=document/press/pc26tab1.html
Department of Defense: Fact Sheet Increasing Transparency in the U.S. Nuclear Weapons Stockpile, 3 May 2010, online: http://www.bits.de/NRANEU/docs/10-05-03_Fact_Sheet_US_Nuclear_Transparency__FINAL_w_Date.pdf (no longer online at: http://www.defense.gov/news/d20100503stockpile.pdf)
Department of State: Transparency in the US Nuclear Weapons Stockpile, 29 April 2014, online: http://www.state.gov/documents/organization/225555.pdf
Kerry, John: Remarks at the 2015 Nonproliferation Treaty Review Conference, 27 April 2015, online: http://www.state.gov/secretary/remarks/2015/04/241175.htm
Weapons in stockpile include active (operational) and inactive (non-operational) weapons in depots. Additional weapons not yet dismantled exit. Secretary of State, John Kerry  announced in April 2015 that about 2.500 weapons were awaiting dismantlement.
4.727 weapons in active or inactive stockpile plus about 2.500 weapons still to be dismantled and 10.251 weapons already dismanteld add up to a total of about 17.478 warheads whose fate or current status has been officially clarified. Compared with the highest number of weapons in active and inactive stockpile in any given year, 31.255 weapons in 1967, this shows, that many more weapons have been built, whose fate needs further explanation and/or greater transparency. Some weapons have been lost. Others have been rebuilt into more modern models. However, can this – together with the above definitions - explain the differences?