The main thing to remember is that nobody is advocating war with either Russia or Teheran. At least I am not. But the Great Game is still alive and kicking. Russia continues to leverage its assets to advance its interests. It uses gas, subversion, even murder. Arguably even murder, in small doses, is diplomacy. But nobody is threatening war.

In that context there is no fatal bar to deploying a limited missile defense. Russia may respond by building a limited number of penetrators to recover theirs strategic flexibility. But ultimately, a small missile defense system does not pose an existential or even a serious threat to Russia. Unless Putin is wholly irrational — which I don’t think he is — the Russian reaction will be proportional.

For the Iranians, with their much smaller (potential) arsenal, a missile defense is much more serious because it nullifies the end result of what they have been working toward. Their ballistic missile program; the fancy warhead designs they may have bought; their centrifuges. The payoff from all that gets heavily discounted by missile defense. If Obama thought about it carefully, he would see missile defense as yet another component of diplomacy. Something to assist him in talking to the Iranians. It is certainly not an act of war, as much as raising a shield against a wrought sword has ever been an act of war. I know it is fashionable, in some countries, to consider wearing body armor a criminal offense, but body armor never killed anyone directly.

Obama’s plea for diplomacy is a little bit like “when did you stop beating your wife”. Iran is being engaged. He may not like the way it is being engaged, but certainly it is the diplomats and not the generals who are dealing with it now.