** FILE ** A Marine officer stands watch as Air Force One, with President Obama on board, arrives at San Francisco International Airport outside San Francisco on Wednesday, April 3, 2013. (AP Photo/Tony Avelar)

Photo by: Tony Avelar

** FILE ** A Marine officer stands watch as Air Force One, with President Obama on board, arrives at San Francisco International Airport outside San Francisco on Wednesday, April 3, 2013. (AP Photo/Tony Avelar)