According to the US Stockpile Stewardship and Management Plan released last month, the development of the United States’ first new nuclear warhead since the Cold War appears to be proceeding.

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This caused a short-circuit that sent a surge of electricity through the launch silo, triggering one of the retro-rockets designed to slow the W-59 warhead down during reentry. The explosion ...

“A rocket sled accelerated the warhead at high speeds and an electric circuit at the end of the track detonated the warhead precisely on target,” says Michael Denigan, principal investigator ...