It looks obvious

Looking at Iran, everybody sees a problem, but not quite the same problem. Hawks see a potential Hitler in Mahmoud Ahmadinejad, the radical Iranian president (who is not, however, the country’s supreme leader). They insist on stopping Iran from developing nuclear weapons by any means necessary, including preventive war. Doves believe that U.S. threats against Tehran are the bigger problem, and that military action would be the biggest problem of all.

Realists see a rising regional power that the United States has little choice but to deal with. Giving a talk in Washington not long ago, Zbigniew Brzezinski, who served as national security adviser in the Carter administration and who is something of an eminence grise among realists, guessed that Iran wants to be a threshold nuclear power like Japan — "not an unreasonable ambition" for a country facing nuclear weapons in the U.S., Israel, and Pakistan, among others. America, he said, may need to accept Iranian nuclear weapons capability, in exchange for nonproliferation inspections and other measures that deter Tehran’s development of actual weapons. In other words: Respect Iran’s power, acknowledge its interests, but contain its ambitions and counter its influence.