Global nuclear stockpiles.

Eight countries are known to possess nuclear weapons: the five acknowledged nuclear-weapon states -- Russia, the United States, France, China, and the United Kingdom -- and three countries -- India, Pakistan, and Israel -- that are not accorded the formal status of nuclear-weapon states under the Nuclear Non-Proliferation Treaty but nonetheless are known to have developed and stockpiled nuclear weapons. North Korea may also have produced a small number of nuclear weapons. (A tenth country, South Africa, also produced nuclear weapons, but it subsequently eliminated its arsenal, becoming the world's first, and so far only, ex-nuclear-weapon state.)

Estimates of the total number of nuclear weapons in the world vary considerably. Nobody, not even the most well informed of the nuclear-weapon states, knows the exact number. Drawing on the work of several US researchers, Project Ploughshares estimates that there are about 31,000 nuclear weapons currently in the global arsenal (see table) -- just under half the number that were in the arsenal when it peaked at about 70,000 in 1986. The explosive power of today's arsenal is equivalent to approximately 500,000 bombs of the size that were dropped on Hiroshima and Nagasaki.

The United States and Russia account for approximately 97 per cent of the global arsenal, with Russia alone accounting for about two-thirds of all the world's nuclear warheads. (There is considerable uncertainty about the exact size of the Russian stockpile, however; the estimate used in the table here could be either high or low by several thousand warheads.)

Strategic nuclear weapons -- the intercontinental-range high-power weapons of global nuclear war -- make up less than half of the global arsenal. The US strategic nuclear arsenal contains about 7,200 operationally deployed warheads. Two thousand of these are mounted on intercontinental ballistic missiles (ICBMs) that are maintained on hair-trigger alert. Another 1,700-1,800 strategic warheads are at sea on US missile submarines at any given time; about half of these are also in position to launch within minutes of an order. The Russian strategic nuclear arsenal contains about 6,000 operationally deployed warheads, roughly 3,600 of which are ICBM warheads on hair-trigger alert. Only one or two Russian missile subs typically are at sea at any given time (48 to 400 warheads, depending on the type and number), but two or more others are maintained at launch readiness while in port. Neither country's bomber force is maintained on alert during normal peacetime.

Global nuclear arsenals (1999)

Russia                20,000
United States         10,000
France                450
China                 400
United Kingdom        185
Israel                100-200
India                 50-80
Pakistan              10-25

Total ~31,000

American and Russian figures include thousands of weapons held in reserve or retired but not yet dismantled. Israeli, Indian, and Pakistani figures represent the potential number of weapons these countries could build, based on estimates of the amount of fissile material they have produced.

Sources:

Nuclear Weapons Database," Center for Defense Information (http://www.cdi.org/issues/nukef&f/ database/nukestab.html);

"Nuclear Notebook," Bulletin of the Atomic Scientist. various editions (http://www.bullatomsci.org/);

"Nuclear Forces Guide," Federation of American Scientists (http://www.fas.org/nuke/guide/summary/htm).

"Current Nuclear Arsenals," Fast Track to Zero Nuclear Weapons, revised edition, Middle Powers Initiatives, 1999.