Of 21 million Americans ages 17 to 21, Mr. Carter said only about one-third are eligible to join the military because of physical and other standards.
Ashton Carter: Defense Dept. must adapt to recruit younger generations →
Carter, who became Pentagon chief just five weeks ago, told troops in Afghanistan last month that the key question should be "are they going to be excellent service members?
Ashton Carter told of concerns over easing transgender ban in military, officials say →