U.S. total megatonnage declined steadily from the mid-1960s (and remained considerably below Soviet megatonnage). The average yield of the U.S. nuclear weapons declined from its peak above 1 megaton to just above 200 kilotons today.
The number of nonstrategic (tactical) nuclear warheads has declined much more sharply than that of strategic warheads, but Russian tactical warheads are expected to remain more numerous than those of the United States.
The total stockpiles of both Russia and the United States today remain above the 10,000-warhead level.
While a tabulation of Soviet nuclear megatonnage is not included in this appendix, total Soviet megatonnage remained considerably higher than that of the United States in the latter part of the Cold War.
The data on U.S. and Soviet/Russian forces are taken from Robert S. Norris and Thomas B. Cochran, ''Nuclear Weapons Databook: U.S.-U.S.S.R./Russian Strategic Offensive Nuclear Forces, 1945-96" (Washington, D.C.: Natural Resources Defense Council, January 1997). The figure on British, Chinese, and French forces is created from NRDC data that appear as a regular feature in the Bulletin of the Atomic Scientists. These data are from "Nuclear Notebook: Estimated Nuclear Stockpiles 1945-1993," Bulletin of the Atomic Scientists, vol. 49, no. 10 (December 1993), p. 57.