Barack Obama contributed this piece to the July/August 2007 edition of Foreign Affairs when he was still a candidate for the Democratic presidential nomination.
Summary: After Iraq, we may be tempted to turn inward. That would be a mistake. The American moment is not over, but it must be seized anew. We must bring the war to a responsible end and then renew our leadership -- military, diplomatic, moral -- to confront new threats and capitalize on new opportunities. America cannot meet this century's challenges alone; the world cannot meet them without America.