Vietnamese Communist Party chief Nguyen Phu Trong doesn't hold an official government post, but it's not surprising that he'll meet with President Barack Obama on his visit to the United States this week. He is the de-facto top leader of his country. More telling is one of Trong's other engagements, a dinner reception hosted by the U.S. Chamber of Commerce, bastion of American free enterprise. Economic imperatives drove the U.S. and Vietnam to normalize postwar relations 20 years ago, and they remain a major incentive to boost ties.