Nuclear Nations

Was reading an article about how Iran is a couple of years away from creating a nuclear weapon.

There seems to be large amounts of contradictory information about Nuclear Weapons. If a 'rogue state' is involved, the sources talk about how difficult it is to make a nuclear weapon - they seem to need to build nuclear power plants first.

When they're talking about terrorism, it suddenly becomes very easy. There's this article from the BBC telling us that basically anyone can make a nuclear bomb, with a couple of important caveats.

Which one is true? How can Iran be two - three years away from a nuclear weapon if all someone needs is a bit of nuclear waste and a bit of chemistry training?

Personally I think the danger from nuclear weapons is exaggerated. If we set off many across the world, there would be a huge disaster. However, one or two bombs wouldn't cause much damage (on a global scale).

Also, why bother keeping them. It may all be a cunning trick. As the important people tell us, we need nuclear weapons so that we can credibly threaen to use them. In order to acheive this goal, all we need to do is convince people we have a nuclear weapon. Convincing people we have a nuclear weapon would be a good use of £10bn...