I am no lover of I'm a Dinner Jacket and his odious colleagues, but I do support the points that Widger makes. If I was Iranian, I'd want nuclear weapons bceasue of all my dodgy neighbours.
The problem with the current confrontation is that the US and EU are painting Iran into a corner and will, through sanctions, cause the already weak economy (inflation +20%, radpidly devaluing currency, high unemployment...) to collapse. Suddenly, the option of inflicting maximum pain on 'The West' by closing the Strait (or even claiming that it is mined) is an attractive option.