Note that the NYT uses Sanger to make a vaguely academic, determinedly confused, purposefully non-judgmental case for the status quo ante in Sunday NYT, "Suppose We Just Let Iran Have the Bomb."
Facts are inconvenient but required alongside the Sanger wandering-around in the groves of think tanks masquerading as anti-Bush Administration policy wonkhood.
1. The UN Charter is a large roadblock to the US doing anything with regard Iran. The UN Charter Chapter 7, article 42, provides for air, land, sea intervention in the event the UNSC votes to sanction a member state as a war-maker. Violation of the NPT by a signatory (Iran) decribes amply what is the UN's idea of war-making. It will take months and perhaps years to get the UNSC to such a series of votes and resolutions, but the process is well-advanced, and history says that once the talk starts, the permanent members get real antsy to get it over with either way.