COLORADO SPRINGS, Colo. - President Obama sent 1,000 Air Force Academy cadets into active duty Wednesday by laying out his vision for a postwar America in which the United States leads beyond the battlefield and by defiantly challenging his critics’ notion of waning American influence.

In a commencement address to the cadets, he hailed a milestone moment as the country winds down its military involvement in the two wars that have defined the generation that has come of age since Sept. 11, 2001.