china vietnam avoid conflict south china sea sunday chinese president xi jinping meet vietnam general secretary nguyen phu trong hours u.s. president donald trump offer mediate maritime dispute relations hanoi beijing particularly strain since july china put pressure vietnam stop oil drill dispute area south china sea vietnam state television say chinese president tell vietnamese leader want work southeast asian nations code conduct sea china xinhua news agency say china vietnam agree properly handle maritime issue strive maintain peace stability reef islands south china sea dispute brunei indonesia malaysia philippines taiwan well china vietnam since philippine president rodrigo duterte grow close china vietnam emerge china main challenger area china move pressure vietnam stop oil drill dispute area july bring relations communist neighbour low xi trump hold bilateral meet vietnamese officials wake summit asia pacific economic cooperation vietnamese city danang trump tell vietnam president tran dai quang prepare mediate claimants south china sea say china position problem trump president quang issue joint statement underscore importance free open access south china sea say party halt escalatory action story refiled fix reverse word order paragraph one vietnam china avoid quarrel south china sea visit