Which country has the most nuclear weapons?

The United States currently owns 9,600 nuclear weapons, while Russia currently owns 16,800. But Russia actually always had more nuclear weapons than the United States.

Russia was lacking in nuclear warheads from beginning of time to 1975. For various reasons, the USSR (and now Russia) have pretty much always had more ICBM weapons than the US, while the US maintained a larger stockpile of gravity bombs, SLBMs, and cruise missiles. Currently, as nuclear-tipped cruise missiles were forbidden under the START I treaty, only bombs, ICBMs, and SLBMs are in existence, with the number of 'usable' weapons varying over time.