In 2014, Communist-ruled Laos and its capitalist neighbor Thailand, which were enemies during the cold war, are set to inaugurate the fourth bridge built across the Mekong River in less than two decades. Western Cambodia gets its electricity from Thailand, and the glittering lights of Bangkok are possible, in part, because of the natural gas that is piped in from Myanmar. And Myanmar says it will start rebuilding its rail line to Thailand — conceived by Japan, built by prisoners during World War II and made famous by the movie “The Bridge on the River Kwai.”