hanoi u.s. president donald trump write vietnamese president tran dai quang promote cooperation two countries government website cite quang say vietnam unite state advance tie new level obama administration amid dispute china south china sea issue trump also express hope strong relationship trump send letter quang affirm wish promote cooperation economics trade regional international issue vietnamese government website say quang make remark meet u.s. ambassador vietnam friday quang emphasize vietnam welcome u.s. efforts improve cooperation countries region maintain freedom navigation aviation u.s. ambassador ted osius report say trump consider attend upcoming asia-pacific economic cooperation apec summit vietnam year vietnam expect one big beneficiaries trans pacific partnership tpp free trade deal trump pull u.s. january hanoi also build link unite state amid maritime dispute china china claim south china sea taiwan malaysia vietnam philippines brunei claim part sea command strategic sea lanes rich fish ground along oil gas deposit prime minister nguyen xuan phuc say last month ready visit unite state promote tie particularly trade trump send letter vietnam 's president promote tie