As of January 2015, the United States maintained a stockpile of approximately 4760 nuclear warheads. This included approximately 2080 deployed nuclear warheads, consisting of roughly 1900 strategic and 180 non-strategic warheads. In addition to this deployed arsenal, about 2680 warheads were held in reserve. Another roughly 2500 retired warheads were scheduled for dismantlement, giving a total inventory of approximately 7260 warheads.
The USA has made slow progress in implementing the 2010 Russian–US Treaty on Measures for the Further Reduction and Limitation of Strategic Offensive Arms (New START). As of 1 September 2014, the USA was counted as having 1642 strategic warheads attributed to 794 deployed missiles and bombers, a modest increase compared with the count in March 2014. The total reduction since the treaty entered into force in February 2011 is 158 strategic warheads and 88 launchers.
Due to the counting rules, however, these numbers do not reflect the actual deployment of strategic warheads and launchers. This is mainly because each bomber is counted as carrying only one weapon, even though the bombers can carry up to 20 nuclear-armed air-launched cruise missiles (ALCMs) each.
Thus far the USA has implemented New START mainly by reducing so-called phantom weapons, that is, launchers that are no longer assigned nuclear weapon missions but are still accountable under the treaty because they continue to carry nuclear-related equipment. This is now changing. The first actual denuclearization of a nuclear launcher—a B-52H bomber—took place in September 2013. Starting in 2015, the US Navy will begin reducing the number of missile tubes on each of its nuclear-powered ballistic missile submarines (SSBN) from 24 to 20. Later in the decade the US Air Force will reduce its intercontinental ballistic missile (ICBM) force from 450 to 400 missiles. It will also remove nuclear capability from all but 60 of its bombers.