When Chinese President Xi Jinping finally congratulated incoming US leader Joe Biden last month, he made clear that security concerns were uppermost in his mind. “We hope both countries uphold the spirit of non-conflict, non-confrontation, mutual respect and win-win cooperation,” was how he began his statement . Xi’s words were not surprising, given the challenges facing US-China relations even under a new Biden administration. Ties between Beijing and Washington have deteriorated over issues ranging from trade , to technology to the origins of the coronavirus – and while the US is not a claimant state in the South China Sea , its policy on the disputed waterway has also altered. Washington views the South China Sea issue as subsumed by the US’ larger quarrel with China. Beijing, for its part, maintains that its maritime claims are grounded in international law – fuelling tensions with other Southeast Asian claimant states and the US. The ongoing dispute has shaped perceptions of China and even resulted in claimant states and some Western countries insisting on negative assumptions about Beijing’s intentions and purposes. In Beijing’s view, there are a number of factors that created turbulence around the South China Sea issue. These include the gradual closing of the window of opportunity to agree on a Code of Conduct with Southeast Asian states , as well as Vietnam ’s energy exploration activities at Vanguard Bank and the talk of it considering new legal actions to stake its maritime claims . Other concerns are Malaysia ’s submission last December under the UN Convention for the Law of the Sea that states there are no potential overlapping claims to its outer continental shelf in the northern part of the South China Sea; and Washington’s muscular and intrusive presence through what it calls freedom of navigation operations in the disputed waters . Time for a reset in US-China relations, foreign minister Wang Yi says Biden’s choice of seasoned professional diplomats for his top foreign affairs and defence posts – such as Anthony Blinken as secretary of state , Jack Sullivan as national security adviser to the White House, and John Kerry as the president’s special envoy on climate issues – does signal a return to the United States ’ traditional liberal diplomatic philosophy. Their appointments also indicate that Biden is aware of the problems with American diplomacy over the past four years. But after emphasising during the election campaign the need to strengthen ties between the US and its allies to restore American leadership, Biden may now seek to multilaterally oppose Beijing in the South China Sea. Such a move would be in stark contrast to his predecessor Donald Trump – who more often alienated allies and tried to single-handedly take on Beijing – and would make any sort of conflict more complicated given the range of parties and interests involved. It is worth remembering that Biden was US vice-president when the Philippines initiated a case at The Hague in 2013 arguing against Beijing’s claims in the South China Sea. He also repeatedly asked China to comply with that arbitral tribunal’s 2016 award, and was a vocal critic of Beijing’s actions in the waterway. Not friends. Not enemies. Where to now for Nato on China? In addition to his past positions on the issue, he now has to confront the Trump administration’s legacy of confrontation – with outgoing US Secretary of State Mike Pompeo issuing in July Washington’s strongest support yet for the 2016 ruling that invalidated China’s maritime claims. As the US continues with its long-standing policy of recognising the arbitration award, we can expect to see more diplomatic and military interactions between it and the Philippines, which itself is set to have a presidential election in 2022 that is likely to usher in a new leadership in need of Washington’s support. Yet the Biden administration’s expected return to a more multilateralist and “lawfare”-based approach in the South China Sea will not negate continuous, intensified military competition between the US and China. Biden may take measures to improve communications between both sides so that a misunderstanding does not become the catalyst for military escalation. But the US is likely to continue dispatching warships, strengthening military coordination with Southeast Asian claimant states and participating in regional security forum mechanisms. This means the Sino-US relationship will not return to what it was in the past. The premise of “all-round competition” between the two sides means the tone of Washington’s South China Sea policy will continue to be defined by toughness. Its allocation of defence and diplomatic resources will stay focused on the Asia-Pacific region, too. Ding Duo is deputy director of the National Institute for South China Sea Studies’ Research Center for Oceans Law and Policy in Hainan, China, and non-resident Research Fellow of the Institute for China-America Studies (ICAS) in Washington, D.C.