Los Alamos National Laboratory

Los Alamos National Laboratory

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What’s in the U.S. Nuclear Stockpile?

For decades, the size of the U.S. nuclear weapons stockpile, and what was in it, remained shrouded in mystery.
July 1, 2013
What’s in the U.S. Nuclear Stockpile?

An unarmed B61 nuclear bomb is test-dropped from a B-2 Spirit Stealth Bomber.


  • Managing Editor
  • Clay Dillingham
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Los Alamos-designed weapons account for approximately 90 percent of today’s nuclear stockpile.
Since reaching a peak of 31,255 weapons in 1967, the U.S. stockpile has gradually declined in size. Today’s stockpile is down to about 2,200 weapons, due in large part to the end of the Cold War and the arms-control treaties that followed. However, there was another very important historical factor driving the downsizing of the stockpile: advancements in nuclear weapons science and technology.
Los Alamos National Laboratory’s contribution to the current stockpile is monumental. Of the approximately 2,200 weapons in today’s stockpile, Los Alamos designs account for approximately 90 percent. The Lab designed five of the seven weapon types in the stockpile. In addition to the Air Force’s B61 nuclear bomb, Los Alamos designed the W78 warhead on the Air Force’s Minuteman III intercontinental ballistic missiles and the W80 warhead on its cruise missiles. Los Alamos also designed the W76 and the W88 warheads on the Navy’s submarine-launched ballistic missiles.