I second Publius’ well-thought-out critique of the "credible threat" tactic we are imposing on Iran.  Publius’ point, in a nutshell, is that by publicly insisting that we are keeping all our options open with respect to Iran — particular the invasion option — we are encouraging Iran to seek deterrent weapons (i.e., nuclear weapons), not discouraging them.

The impetus to protect oneself is so patently obvious that I am somewhat astounded that those on the right — you know, people who think everyone should have a gun in their household — can’t see the wisdom of it.  When people, and by extension, countries, see a credible threat by a far-more-powerful force, they gear up to defend themselves.  A nuclear weapon is the ONLY thing that Iran can possess to deter the threat from us, so of course they’re going to work hard to get the bomb, especially since we make rumblings that we’re a-comin’.