The Limits of "Diplomacy"

I've had this nagging disquiet with the Democrats' diplomacy-talk on Iran, and now Josh Marshall formulates it well:

But another point -- diplomacy is a tactic, not a strategy. Our whole strategy is wrong in the region. Leaving more time for the diplomatic phase of the policy just delays getting to where the policy is taking us: full-scale war with Iran.

Right. The question isn't "do we use diplomacy?" the question is what are we trying to do — are we talking about a good faith effort to deal with the Iranian nuclear program in the context of a larger effort to put our polices in the region on the right track, or is the diplomacy part of a larger effort to portray events in the Middle East as a zero sum conflict between the US and Iran.