Manila - Philippine President Rodrigo Duterte faced little support on Saturday at a regional summit in his efforts to weaken Southeast Asian resistance to Chinese expansionism in the contested South China Sea, diplomats said.Duterte was due to release a chairperson's statement at the end of the one-day Association of Southeast Asian (ASEAN) leaders meeting that ignored an international tribunal ruling rejecting China's sweeping claims to the strategically vital waterway.Reefs and shoalsAhead of the summit Duterte said the Philippines and other nations were helpless to stop Chinese artificial island building in areas they claimed, so there was no point discussing it at diplomatic events such as Saturday's summit."It cannot be an issue anymore. It (Chinese presence) is already there. What would be the purpose also of discussing it if you cannot do anything," said Duterte.But diplomats said other ASEAN nations, unhappy with intense Chinese lobbying of the Philippines, had sought to toughen up the chairman's statement and there were hot debates on the issue leading up to the summit.China has been turning reefs and shoals in areas of the sea claimed by the Philippines and other nations into artificial islands and installing military facilities there.The United States has criticised the construction work, warning against militarisation in the waterway where $5 trillion in annual trade passes.ASEAN members Vietnam, Malaysia and Brunei also claim parts of the sea, but China insists it has sovereign rights over nearly all of it.Island buildingThe Philippines, under previous president Benigno Aquino, had lobbied hard at ASEAN summits for the bloc to voice its strong opposition to the Chinese expansionism and official statements at those events often reflected that.Aquino also filed a case at a UN-backed tribunal asking it to reject China's claims and artificial island building.The tribunal last year ruled largely in the Philippines' favour. But the ruling came after Duterte took power.