W56
The W56 was an American thermonuclear warhead produced starting in 1963 which saw service until 1993 , on the Minuteman I and II ICBMs . 
<triplet> W56 <subj> thermonuclear warhead <obj> instance of <subj> 1963 <obj> inception <subj> 1993 <obj> service retirement <triplet> Minuteman I and II <subj> ICBM <obj> subclass of