Goodness. I'm not suprised, but this is essentially an act of war by Iran on Britain and Iraq (and by extension the United States).
Any troop withdrawls out of Iraq or Afghanistan have to be postponed for the time being, and non-conventional forces (ie special forces, naval/air force/marines) have to be built up in the Middle East. Because, chances that there will be a war with Iran over the next few years are fairly high (I'd say 50-50). Even assuming there isn't, action should be taken - hard line on sanctions, no nuclear plants, maybe a MOAB or two on their chief nuclear research facilities.
Why? It is pretty much self-defense.
Too bad Saddam is gone. 
Too bad, he can't a few more hundred thousand Iranians. [/sarcasm]
