Status of World Nuclear Forces 2008a

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The exact number of nuclear weapons in each country's possession is a closely held national secret. Despite this limitation, publicly available information and occasional leaks make it possible to make best estimates about the size and composition of the national nuclear weapon stockpiles.

 

The information available for each country varies greatly, ranging from the most transparent nuclear weapons state (United States) to the most opaque (North Korea). Accordingly, while the stockpile for the United States is based on real numbers, the North Korean stockpile is highly uncertain. Indeed, although U.S. Intelligence claims that North Korea may have assembled a few nuclear weapons and North Korea claims to have some, no information is available in the public domain that proves that North Korea has assembled a nuclear weapons much less has an operational nuclear weapon.

 

To develop these arsenals, the nuclear powers have conducted over 2050 nuclear weapons tests since 1945. Historically, nuclear tests were primarily proof-tests to verify that a new weapon worked as designed. Some tests also served to check for potential defects in deployed weapon types. The United States and the Soviet Union agreed to move nuclear tests underground in 1963, and since then other nations have gradually followed. The last atmospheric test was conducted by China in 1980. India and Pakistan in 1998 both announced that they had conducted five tests, but only three and two, respectively, were detected. North Korea announced on October 8, 2006, that it had conducted a nuclear test.