The decision to not go with the development of extremely large thermonuclear weapons might count - the US Sundial Project was supposed to be about 10 gigatons of TNT. Not the most practical weapons but once you get to a certain size delivery arguably stops being a problem - its going to kill everyone anyway so doesn't matter where you let it off!

https://en.wikipedia.org/wiki/Sundial_(weapon)

Edit: Mind you, I wonder if the design for Sundial is stored somewhere...