For decades, a delicate strategy of deterrence kept Russia and the US from nuclear war. With China upping its nuclear ambitions, things are about to get a lot more complicated. 
This episode was produced by Amanda Lewellyn, edited by Matt Collette, fact-checked by Laura Bullard, engineered by Michael Raphael, and hosted by Noel King.
Transcript at vox.com/todayexplained
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