If there is one lesson for U.S. foreign policy from the past 10 years, it is surely that military intervention can seem simple but is in fact a complex affair with the potential for unintended consequences.

In a very weak economy, when you say 'cut government spending,' what you mean is you're laying off school teachers and you're de-funding various programs that put money into the economy. This means you have more unemployed people that then draw unemployment benefits and don't pay taxes.

Iran is a country of 80 million people, educated and dynamic. It sits astride a crucial part of the world. It cannot be sanctioned and pressed down forever. It is the last great civilization to sit outside the global order.

But as the arms-control scholar Thomas Schelling once noted, two things are very expensive in international life: promises when they succeed and threats when they fail.

Having your fiscal house in order and having a more manageable macro-economic future is going to be very useful in creating growth.