Graduating Air Force Academy cadets assemble in unison for their graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Graduating Air Force Academy cadets prepare to assemble in unison for their graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Graduating Air Force Academy cadets listen during their graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Graduating Air Force Academy cadets hug as they receive diplomas during their graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)A graduating Air Force Academy cadet holds her newly-received diploma aloft, gesturing to members of the audience, during the graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)U.S. Air Force Academy Class of 2015 top graduate, senior cadet Rebecca Esselstein smiles during the graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Graduating Air Force Academy cadets hug as they receive diplomas during their graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)A graduating Air Force Academy cadet straightens his cap during the graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Graduating Air Force Academy cadets applaud during their graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)A graduating Air Force Academy cadet smiles during the graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Graduating Air Force Academy cadets hug as they receive diplomas during their graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)U.S. Air Force Academy Superintendent Lt. Gen. Michelle Johnson speaks during the graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Air Force Academy graduates throw their caps into the air as F-16 jets from the Thunderbirds make a flyover, at the completion of the graduation ceremony for the class of 2015, at the U.S. Air Force Academy, in Colorado Springs, Colo., Thursday, May 28, 2015. (AP Photo/Brennan Linsley)Stephen Perme hugs his mother Barbara after the Air Force graduation parade held at the Academy on Wednesday, May 27, 2015, in Colorado Springs, Colo. The Class of 2015 graduation will be held on May 28 inside Falcon Stadium at the Air Force Academy. (Logan Riely/The Gazette via AP) MAGS OUT; MANDATORY CREDITCadet Landon Kinsey carries his girlfriend Hailey Jacob while walking with his sister Jenna Kinsey through the muddy field where the annual Air Force graduation parade was held to honor the Class of 2015 on Wednesday, May 27, 2015, in Colorado Springs, Colo. The Class of 2015 graduation will be held on May 28 inside Falcon Stadium at the Air Force Academy. (Logan Riely/The Gazette via AP) MAGS OUT; MANDATORY CREDIT