In a 20,000-word essay, Atlantic journalist Jeffrey Goldberg has offered the best explanation yet for U.S. President Barack Obama's foreign policy. "The Obama Doctrine" reveals a cool-headed thinker, a realist— someone with a true understanding of the limits of power — who both appreciates and somewhat resents the role of the United States as the world's "indispensable power."

The first key point to take away is that Obama thinks long and hard about foreign policy and, most importantly, about the appropriate use of power and the meaning of leadership. His is not a reflexive approach to U.S. engagement with the world; it reflects deep thought about, continued grappling with and considerable skepticism toward the guiding principles of American foreign policy.

For Obama, "real power means you can get what you want without having to exert violence." He does not believe in posturing, chest-thumping or bullying. Instead, he seeks to unite governments in pursuit of shared interests and concerns. Washington leads by marshaling coalitions, setting agendas and making it possible for diverse nations to work together, each contributing its own perspectives and resources. This is the classic application of "soft power," Harvard Professor Joseph Nye's notion that power reflects the ability to get other countries to join your efforts willingly, in the belief that what you want is also good for them. This approach also means that one of the most important things the U.S. can do is to get its own house in order. The U.S. must be strong at home, with both physical resources and moral strength, before it can claim to lead others. This belief animated Obama's first National Security Strategy. It is sometimes mistaken for a desire to disengage, but that is a misreading of his intentions.