US President Donald Trump said on Sunday he was prepared to mediate between claimants to the South China Sea, where five countries contest China’s sweeping claims to the busy waterway. Trump was speaking in Vietnam, which has become the most vocal opponent of China’s claims and its construction and militarization of artificial islands. Meanwhile, Philippines President Rodrigo Duterte said on Sunday the South China Sea dispute was “better left untouched”. Trump arrived in the Philippines on Sunday. Trump’s knack for diplomatic flattery will be tested in the Philippines on Monday when he and Philippines President Rodrigo Duterte meet for a state visit.