@cbsmornings: Then-Air Force Major Dan Caine, now the chairman of the Joint Chiefs of Staff, was one of the military pilots sent to protect the airspace. They were told they may need to shoot down any planes that threatened the nation’s capital on September 11, 2001. He told @Norah O’Donnell what was going through his mind that day: "I felt like that responsibility was one that I needed to hold, and I was mindful of the consequences, while not dwelling on them." More from their interview airs tonight during our primetime special, “9/11: We Remember.”