Randy:

I think there is a clear objective (no Iranian nuclear weapons), and a clear-ish strategy (which you correctly identify as using "the quasi-coercive lever of sanctions to get them to stop," while offering the hint of greater future engagement in trade and other forms as an implied incentive if they do).

Whether it is a strategy that is likely to work--and indeed, whether there is any possible strategy that is likely to work--is another question.

Why it is the West doesn't want a nuclear Iran raises some interesting questions about motives (Slapout) and the inherent contradictions of the policy. Typically, three reasons are put forward for attempting to prevent Iran from becoming a nuclear power:

1) Iranian nukes would strengthen Iran's regional influence. Obviously, this rationale is one which, on the Iranian side, only makes the prospects of of nuclear capacity more appealing.

2) Iranian nukes would go rogue, whether because the Iranian leadership are reckless, or due to some future instability. No one in Iran actually believes this, so it has little traction there even if it plays well elsewhere.

3) Iranian nukes would spark a regional arms race that would leave everyone less secure. This is an argument which finds some receptivity in Tehran as well as Washington.

Compounding all of this is the probable absence of a clear policy on the Iranian side. It is not at all clear that Tehran has taken the decision to build a weapon, as opposed to the decision to build the things that would one day allow it to build a weapon should it decide to do so. The issue is also overlaid with Iranian domestic politics--to the point that when Ahmedinejad appeared to be signalling some flexibility, he was criticized by the Green movement reformist for appeasement of the West.