Last year saw the situation in the South China Sea deteriorate as the United States, other extra-regional powers and some littoral states made waves despite the global impact of Covid-19. Four features stand out in the current situation. First, the “militarisation” of the South China Sea has intensified, spearheaded by the US and joined by other extra-regional countries. Second, references to the 2016 Hague ruling against China in the South China Sea have been revived, and a new round of legal tussles is about to begin. Third, consultations on a code of conduct in the South China Sea have stalled due to unforeseen events and external interference. And, fourth, US-Vietnam interactions in the region carry clear strategic intentions aimed at China. The international political and economic landscape is changing. As the code of conduct consultations approach the final stages, there are leadership changes in the US and some South China Sea littoral states. In the US, President Joe Biden is expected to maintain some continuity in South China Sea policy . Vietnam may well become more assertive in its South China Sea claims after the dust settles on its political leadership changes . And, as the Philippines enters presidential election season , relations with China will again be tested by South China Sea issues. Given this background, the situation will only become more complex, volatile and prone to conflict in 2021. In the coming years, international law and rules will mainly govern how the situation evolves. As vice-president, Biden repeatedly stressed China should abide by international rules and accept the 2016 arbitration ruling in favour of the Philippines. As president-elect, he emphasised the importance of China playing by international rules in US-China relations. In Biden’s administration, “rules diplomacy” will probably be the top priority for US policy on the South China Sea. Under Biden, the US is likely to mobilise its resources and rally allies and partner countries to keep up the South China Sea hype, and push the narrative that the arbitration award is part of international law and rules. It may also encourage Vietnam to sue China over South China Sea claims in the same international court of arbitration, while covertly supporting actions by Vietnam, the Philippines and Malaysia based on the ruling. The US is also likely to craft a new legal design for its freedom of navigation operations and “substantiate” the arbitration award with military action. Under US inducement and coercion, some claimants preoccupied with the arbitral award could make a move, citing international law and rules. For example, the Philippines is said to be accelerating a constitutional amendment process to include the arbitration award in its constitution, while Malaysia’s attitude is hardening over its 2019 submission to the UN Commission on the Limits of the Continental Shelf to establish its outer limits in the northern waters of the South China Sea. Some extra-regional countries may follow the US in seeking geopolitical interests in the South China Sea with their military presence, bringing the internationalisation of the issue to a new stage. Japan, for example, is likely to respond actively to US requests for joint operations, given overlapping Sino-Japanese claims in the nearby East China Sea, as will Australia, a loyal American ally in the Indo-Pacific strategy. Britain and France are almost certain to send warships into the South China Sea in 2021, given their own strategic interests and US support. Other claimant countries, backed by the US, are likely to take provocative actions to consolidate and expand their interests as the window narrows for the code of conduct consultations. With US backing and the need for post-Covid-19 economic recovery, Vietnam may capitalise on the growing political consensus in the South China Sea to once again risk pushing forward its oil and gas project in the Wanan Tan waters, known as Vanguard Bank, and in the Blue Whale gas field. If a maritime conflict were to flare up between China and Vietnam over oil and gas exploration in contested areas, the US would give robust support to Vietnam as a vanguard in US efforts to contain China. Vietnam may then be emboldened to seek international arbitration on its disputes with China in the South China Sea. Malaysia may also seek to bring under its effective control the waters of Beikang Ansha and Nankang Ansha, known as Luconia Shoals , through oil and gas drilling activities in the disputed areas. The code of conduct consultations are also mired in difficulty. Despite all the efforts since 2017 by China and Asean, the prospect of concluding consultations by the end of the year is dim. This is due to interference by some extra-regional countries, the tough positions taken by a small number of claimant countries amid demands to extend the consultation window, the fallout over the arbitration award and divergent interests. The US is also likely to join other extra-regional countries to influence the process in new ways, whether through official statements or think tank reports. For the countries in the region, the South China Sea is not only home but also a platform to build a maritime community with a shared future. China and Asean should put aside their disputes, forge a consensus, focus on cooperation and commit to building rules and order. Following the “dual-track approach” China introduced, Asean members need to work more closely to speed up the code of conduct consultations while also promoting practical cooperation under the framework of the Declaration on the Conduct of Parties in the South China Sea. That way, they can contribute anew to building peace, friendship and cooperation across the South China Sea. Wu Shicun is president of China’s National Institute for South China Sea Studies and chairman of the China-Southeast Asia Research Centre on the South China Sea