The Pentagon has outlined how it wants to revamp the US nuclear arsenal, and develop new low-yield bombs, largely in response to the threat from Russia.
Reality Check looks into where the world's nuclear weapons are located and who owns them.
While the global stockpile of nuclear weapons has shrunk significantly since the Cold War, there are hundreds of warheads that could be launched at short notice, and experts say every nuclear-armed nation is modernising its arsenal or has plans to do so. Read more at :
http://www.bbc.com/news/world-42873633