U.S. Strategic Nuclear Forces: Background, Developments, and Issues. Amy F. Woolf, Specialist in Nuclear Weapons Policy. March 6, 2018.
“…At the present time, the U.S. land-based ballistic missile force (ICBMs) consists of 400 land-based Minuteman III ICBMs, each deployed with one warhead, spread among a total of 450 operational launchers. This force is consistent with the New START Treaty. The Air Force is also modernizing the Minuteman missiles, replacing and upgrading their rocket motors, guidance systems, and other components, so that they can remain in the force through 2030. It plans to replace the missiles with a new Ground-based Strategic Deterrent around 2029.The U.S. ballistic missile submarine fleet currently consists of 14 Trident submarines. Each has been modified to carry 20 Trident II (D-5) missiles—a reduction from 24 missiles per submarine—to meet the launcher limits in the New START Treaty. The Navy converted 4 of the original 18 Trident submarines to carry non-nuclear cruise missiles. Nine of the submarines are deployed in the Pacific Ocean and five are in the Atlantic. The Navy also has undertaken efforts to extend the life of the missiles and warheads so that they and the submarines can remain in the fleet past 2020. It is designing a new Columbia class submarine that will replace the existing fleet beginning in 2031…”