US President Donald Trump’s offer to mediate the long-standing territorial disputes in the South China Sea could antagonise Beijing and overshadow his relationship with Chinese President Xi Jinping. The maritime disputes have long been a sore point in China’s relations with the United States, Vietnam and other Asia-Pacific countries, with Beijing insisting the disagreements must be resolved through negotiations with the countries directly involved, and Washington, which is not a claimant, has no role to play in the talks. Trump’s offer in Hanoi on Sunday came just hours before Xi started his second state visit in three years to the former communist ally, which has emerged in the past year as the most vocal opponent of China’s expansive claims and militarisation of artificial islands in the contested waters. “If I can help mediate or arbitrate, please let me know,” Trump said at a meeting in Hanoi with Vietnamese President Tran Dai Quang. “I’m a very good mediator and arbitrator.” ‘I’m a very good arbitrator’: Donald Trump offers to mediate on South China Sea disputes Like his hardline speech on Friday to the Asia-Pacific Economic Cooperation (Apec) forum in Da Nang, where he lashed out at China’s “territorial expansion”, Trump acknowledged again that China’s position on the South China Sea was a problem. But his Vietnamese counterpart did not respond directly to Trump’s offer. Instead, Quang said: “It is our policy to settle disputes in the South China Sea through peaceful negotiations” with “respect for diplomatic and legal process in accordance with international law”. Beijing’s claim to the energy-rich South China Sea covers almost 90 per cent of the waters and overlaps those of Vietnam, the Philippines, Malaysia, Brunei and Taiwan. Philippine President Rodrigo Duterte was equally wary of confrontation, saying the dispute was “better left untouched”. “We have to be friends. The other hotheads would like us to confront China and the rest of the world on so many issues,” Duterte said, returning home from Apec to host the Asean and East Asia summits in Manila. “The South China Sea is better left untouched, nobody can afford to go to war.” Philippine Foreign Secretary Alan Peter Cayetano said that while he would not speak for the Association of Southeast Asian Nations, Manila would continue its bilateral negotiation with Beijing. “We thank [Trump]. It’s a very kind and generous offer because he is a good mediator. He is the master of the art of the deal,” Cayetano said. “Not one country can just give an instant reply because mediation involves all of the claimants and non-claimants.” The South China Sea is a busy and important waterway where about 30 per cent of global maritime trade and about half of all global oil tanker shipments pass through annually. Trump’s take on China in Vietnam was a sharp change in tone from just days earlier in Beijing where the US leader boasted of his personal bond with Xi and avoided confrontation in public on contentious issues, including the South China Sea. Observers said that sudden shift was a reality check for US-China relations. They said Trump’s remarks, which gave few clues as to what he planned to do next, would reinforce Beijing’s suspicion that Washington intended to meddle in South China Sea affairs and stir trouble to contain China. Despite Beijing’s repeated protests, the Trump administration has carried out four freedom-of-navigation patrols close to Chinese-controlled islands this year, including one last month. “China does not want the US to mediate in the South China Sea disputes because of its concerns about US meddling,” said Wu Xinbo, a US affairs specialist at Fudan University in Shanghai. Wu said Washington had refused to heed Beijing’s concerns and cease the patrols, and Trump’s latest remarks on the maritime disputes seemed to be an attempt to stoke tensions to counter China’s expanding influence in the region. “Vietnam has pinned its hopes on Washington to rein in China, and Trump’s latest offer shows they are colluding on the South China Sea issue,” he said. Hanoi’s warming ties with Washington and its surging anti-China sentiment will also hamper Xi’s fence-mending visit to Vietnam. In July, China pressured Vietnam to stop drilling for oil in a disputed area, taking relations to a low. Xi’s last visit in 2015 was overshadowed by violent anti-Beijing protests over another oil stand-off in the South China Sea the previous year. Forget the Xi-Trump bromance, it’s time the US came clean on its vision for China and Asia Bui Thi Thu Hien, a China expert from the Institute of Chinese Studies at the Vietnam Academy of Social Sciences, said Vietnam, as the smaller neighbour, was concerned that China would become more assertive after Xi’s consolidation of power at the Communist Party’s national congress last month. “With China’s rise, its competition with other major powers is inevitable, which could lead to regional instability that affects all countries,” she said. Alexander Vuving, a China expert at the Daniel K Inouye Asia-Pacific Centre for Security Studies in Honolulu, said that despite Beijing successfully appealing to Trump’s ego and softening Trump’s rhetoric on China last week, there was little change to the fundamentals of US-China relations. He said that although Trump and Xi appeared to have good personal ties, Beijing’s relations with Washington would be tested at the Asean and East Asia summits in the Philippines by the US leader’s embrace of a quadrilateral alliance with Japan, India and Australia. “[The resumption of the four-way alliance] is the budding element of a new regional security architecture [targeting China],” Vuving said. Additional reporting by Laura Zhou in Manila, Kristin Huang, Reuters and Bloomberg