Natanz is a city south of Tehran, the nation’s capital, and is where nuclear enrichment activities are taking place. While the Chicago Tribune, as usual is riddled in errors in its international reporting, stated 1000 centrifuges were at Natanz, the number is closer to 164 which is a big difference if one is assessing the state of nuclear development. Iran would need 1000s of centrifuges in order to enrich uranium at a level in which it could be used as an explosive device in a bomb. While Iran is hailing its uranium enrichment programme as a great success many nations do it for industrial or electricity purposes. From Japan to Finland to Sweden to Belgium to Spain, nations that use nuclear power enrich uranium to around 3-5% to run a nuclear power plant. The technology is widely available. Yet many nations that use nuclear fuel choose not to develop nuclear weapons but to confine their nuclear programmes to medicine, electricity and the like.
The United States enriched uranium at their Y-12 plant at Oak Ridge in Tennessee as part of its Manhattan Project outrage to develop the atomic bomb during World War II. The decision to make the bomb was based on faulty intelligence and a misguided assumption that Germany was pursuing avidly and successfully a nuclear option. Such was not the case and the bomb of course need not have been built and certainly not used against a defeated, non-nuclear adversary of Japan.
The uranium bomb dropped on Hiroshima was never tested. The confidence in a gun-type assembly in which one sphere of uranium would be shot into another to create critical mass was a given and only a plutonium device was tested at Trinity on July 16, 1945. I am sure if Iran develops a nuclear device it may well decide not to test it. It would be difficult for it to build a test-site and escape detection unless it leaves the N.P.T. and decides to abandon any restraints on its programme. North Korea has not tested a weapon and is presumed to have a few atomic bombs.
Israel, a nuclear state, may have tested in 1979 along with South Africa a nuclear explosion in the south Atlantic, the "flash in the sky." However, it has developed both A-bombs and most likely thermonuclear devices without testing the latter. So a nation may go nuclear and not test its weapons. North Korea, if nuclear, has not tested. Israel may have tested one A-bomb but not an H-bomb. No other nation that has nuclear weapons has avoided any testing. Indeed the U.S., Russia, U.K., China, France, India and Pakistan are all nuclear-weapons states and have tested the devices. Well I am assuming India and Pakistan have nuclear weapons although I do not think they are deployed or on alert status. Given their testing and the dynamics of South Asia's dynamic, I imagine they have nuclear tipped missiles or bombs that are in storage some place.