5,113

That's the number of nuclear warheads in the U.S. arsenal.  Disclosed to the public for the first time (ever, as far as I know!).  Obama hopes that this transparency will help build confidence in the U.S. disarmament agenda.

Oh, and, the largest arsenal we've had:  31,225 nuclear warheads in 1967.

For more:  Reuters update on the NPT discussions