[Centurion2000]

The general consensus seems to be that about 5 atomic or nuclear weapons have been used in anger, including ours on Japan.

What .. 2 in Japan and 3 on the Soviet-Sino border wars ?

Wasn't there also an unexplained nuclear detonation underwater in the Indian Ocean right about the time that Taiwan, SouthAfrica and Israel were rumored to be collaborating on a nuke?

[Spktyr]

Yup. There may have been more, but nobody's talking.

And yes, there was an unexplained subsurface nuclear detonation in the middle of the Indian Ocean on 22 Sep 1979. The South Africans finally claimed it as theirs in 97, then backpedalled. Officially, it's still unclaimed.

http://www.globalsecurity.org/wmd/world/israel/nuke-test.htm