WASHINGTON - President Barack Obama on Sunday heads to Vietnam and Japan intent on building stronger economic and security ties with Asian-Pacific allies anxious about the rise of an increasingly muscular China. That forward-looking message will be delivered even as Obama confronts the legacies of two wars long past - Vietnam and World War II.

Obama is eager to upgrade U.S. relations with Vietnam, whose rapidly expanding middle class beckons as a promising market for U.S. goods. He also hopes stronger ties will help to offset China's growing strength in the region. During his three-day stay in Vietnam, Obama will make the case for stronger commercial and security ties, including approval of the 12-nation trans-Pacific trade agreement.

The president's stay in Japan will include a historic visit to Hiroshima.