Looks like white tennis shoes.
As opposed to boots? In any case, it certainly doesn't appear that he is with the US military as at least one person here suggested he might be. In fact, he may be a foreign national.
"No details about the passenger were immediately released, and the bus remained parked in downtown Portsmouth with a bomb squad on the scene. The man could be a foreign national, as agents from the U.S. Immigration and Customs Enforcement were on the scene and there were reports an interpreter was needed to speak to him."
http://news.yahoo.com/s/ap/20100507/ap_on_re_us/us_bus_bomb_threat_26
“Looks like white tennis shoes. “
Disgruntled, middle-aged white tennis shoes, cling to concrete and asphalt!