text:  Trong, who's stepping back to receive treatment for an unspecified illness. Mickey Bristow reports. Mr. Trong has been the most powerful man in Vietnam's one-party state for more than a decade. But over recent months, he's appeared fragile and has missed a number of key meetings. An official statement said he was stepping back to focus on his health. He'll be replaced by Tho Lum, a former security minister who was made president only in May.