Stephen Walt writes: Will the U.S. and the rest of the P5+1 manage to turn a potential diplomatic breakthrough with Iran into another counterproductive failure? It’s too soon to tell, but betting on failure has been the smart wager in the past.

The Baghdad talks between Iran and the P5+1 apparently got a lot of serious issues on the table, but didn’t achieve a breakthrough, let alone an agreement. The main reason is the hardline position adopted by the United States and its partners, and especially our refusal to grant any sort of sanctions relief. The parties will resume discussions in Moscow in June.

From a purely strategic point of view, this situation is pretty simple. Iran is not going to give up its right to enrich uranium. Period. If the West insists on a full suspension, there won’t be a deal. It’s that simple. At the same time, the U.S. and the rest of the P5+1 would like to maximize the amount of time it would take Iran to “break out” and assemble a weapon. The best way to do that is to limit Iran’s stockpile of enriched uranium to concentrations of less than 5 percent. If Iran insists on keeping a large supply of 20 percent enriched uranium on hand, we’ll walk too.

So there you have the outline of the deal–we accept low-level enrichment and lift sanctions, and Iran gives up the 20% stuff–although there are other details what will have to be worked out too. Frankly, given where we are today, it’s surprising the U.S. isn’t grabbing that deal with both hands. Why? Because unless the U.S. is willing to invade and occupy Iran (and we aren’t) or unless we are willing to bomb its facilities over and over (i.e., every time Iran rebuilds them), there is no way to prevent Iran from having the potential to obtain nuclear weapons if it decides it wants to. They know how to build centrifuges, folks, and the rest of the technology isn’t that hard to master. So the potential is there, and there’s no realistic way to eliminate it.

The smart strategy, therefore, is to keep them as far away from the bomb as possible, and to reduce Iran’s incentive to go all the way to an actual weapon. And the best way to do that — duh! — is to take the threat of military force off the table and to stop babbling about the need for regime change.