Together, we have met great challenges. But as we enter this new chapter in our shared history, profound challenges stretch before us. In a world where the prosperity of all nations is now inextricably linked, a new era of cooperation is required to ensure the growth and stability of the global economy. As new threats spread across borders and oceans, we must dismantle terrorist networks and stop the spread of nuclear weapons, confront climate change and combat famine and disease. And as a revolution races through the streets of the Middle East and North Africa, the entire world has a stake in the aspirations of a generation that longs to determine its own destiny.