SOME old soldiers don’t even fade away. They keep on fighting, trapped in their own past as the world around them changes, ghosts of a long-dead war. “I have the duty to liberate my country!” shouted Ly Tong, wearing bright yellow prison pajamas, through a double screen of wire mesh at Bangkok’s central jail. “The only thing that matters is, the Communists still control my country,” he shouted over the hubbub in the caged visiting area recently. “I’m a pilot. This is what I can do.” His country is Vietnam and the Communists have controlled it since 1975, when they...