I like how "contingency plan" = OMG WAR FOR SURE!!!!!!!
I don't think the U.S. or the UK is really frothing at the mouth to attack Iran. Certain elements (Republicans in Congress), sure, I'll give you that. But after two costly wars that wasted billions which could have been spent at home on any number of projects, with a public that's sick of war and is happy to have our troops out of Iraq and Afghanistan as soon as possible? If Iran gets invaded, people will march on Washington with pitchforks, torches, guns, whatever it takes to get our current leadership removed. There is zero appetite for any more invasion bullshit.
And can we knock off the whole self-hating American stuff? It's one thing to be upset at our government and the messes they get us into. I'm quite pissed myself, but I don't run around saying it'd be ok and justifiable for U.S. forces to die just because someone bombed Iran's nuke facilities (namely, Israel in this case, who has done it to Syria and Iraq before).
EDIT: Oh, and China and Russia are Iran's buddies. Any invasion and they will come down on the U.S. itself.