They do have a deterrent capability, in as far as a would be aggressor would think twice before striking the country since they know Iran can strike back. In fact that has been the stated use of such weapons since the 1950s by all those who have deployed them. Why would Iran be any different?
As the empire unravels, it's provinces fall into disarray.
Reading a recent article in Politico (http://www.politico.com/magazine/story/2015/04/israel-nuclear-weapons-117014.html#.VTUTr5OrHHQ) describes how Israel got hold of nuclear weapons. And it did so by doing the very same things it now blames Iran of doing.
They do have a deterrent capability, in as far as a would be aggressor would think twice before striking the country since they know Iran can strike back. In fact that has been the stated use of such weapons since the 1950s by all those who have deployed them. Why would Iran be any different?