When Julius Caesar’s army defied Roman senate orders and crossed the Rubicon river, it kicked off a civil war. Some say US-China relation s have crossed their Rubicon and the two countries will spiral inexorably towards kinetic conflict. War may not be inevitable but it is increasingly likely. China and United States are on a collision course driven by competing ideologies, ambitions and visions of international order. Compromise and coexistence would require China to abandon some core interests or the US to accommodate some of them. Neither seems inclined to do so. Both claim to not want conflict yet cannot agree on how to avoid it. They are stuck in a circle of geopolitical and military gamesmanship centring on the South China Sea – with critical security implications for the region and beyond. US President Joe Biden believes the world is at a turning point. He has publicly identified what he considers an existential threat to democracy and thus, Americans’ beliefs and way of life. He says autocracies such as China and Russia bet their systems will outcompete democracies in addressing the enormous and increasingly complex challenges of the 21st century. He says they think democracies, with their Byzantine systems of checks and balances, will neither be efficient nor effective enough to meet these challenges and people’s expectations. But the differences are more fundamental. The late Lee Kuan Yew hit the nail on the head: “For America to be displaced [ …] in the western Pacific, by an Asian people long despised and dismissed with contempt [ …] is emotionally very difficult to accept. The sense of cultural supremacy of the Americans will make this adjustment most difficult.” China sees the US approach as arrogant and imperious. As Graham Allison observed: “Washington urges other powers to accept the rule-based international order over which it presides. But through Chinese eyes, it looks like the Americans make the rules and others obey Washington’s commands .” President Xi Jinping has stated that China will not be “ bullied, oppressed or subjugated ”, nor will it evolve in directions set by others. Government adviser Shi Yinhong says that the leaders have deemed changing the fundamental policy “not possible, or at least not worth it”. Foreign Minister Wang Yi laid out the specifics of China’s position to US Deputy Secretary of State Wendy Sherman in their July 26 meeting in Tianjin. The bottom line is that the US must not challenge or seek to subvert China’s model of governance, interfere in China’s development, or violate China’s sovereignty or harm its territorial integrity. But the US continues to do all three. Vice Foreign Minister Xie Feng told Sherman that the relationship was “in a stalemate and faces serious difficulties” because some Americans see China as an “ imagined enemy ”. Indeed, the China “threat” now drives US military planning and foreign policy. The US is applying “whole of government” pressure on China – instituting sanctions because of what it considers unfair economic practices, its theft of intellectual property, government-linked cyber hacking , harsh treatment of minorities in Xinjiang , political crackdown in Hong Kong and its bullying in the South China Sea. Threatening a core Chinese interest, the US is stepping up diplomatic relations with Taiwan and supplying it with ever more powerful weapons. This clash of world visions is backed by military shows of force in magnitudes unseen since the Cold War. China’s navy now poses a credible challenge to US military dominance in the region. The US response is to build political and military coalitions of like-minded democracies to contain China. There are three areas where unilateral action could trigger war – Taiwan, the East China Sea and South China Sea. The first two are the most dangerous but also have clear red lines, so China, Japan and the US are likely to avoid kinetic conflict for now. In the South China Sea, the red lines are more ambiguous but just as real. Under president Donald Trump, the South China Sea situation rapidly deteriorated. Amid belligerent rhetoric and military posturing, both sides became locked in a dilemma driven by distrust. Each claimed to be responding to the other and neither wanted to de-escalate first. A clash became a distinct possibility. Both militaries began preparing for the worst. The Biden administration has continued and even intensified this military posturing. On the eve of his visit to Southeast Asia last month, US Defence Secretary Lloyd Austin said he intended to emphasise a commitment to freedom of the seas and push back on China’s “unhelpful and unfounded claims” in the South China Sea. He said he would be “working closely with our partners about how we’re updating and modernising our capabilities and their own capabilities to work together to tackle some changing forms of aggression and coercion [and] about how we’ll work hand in hand to pursue our new vision of integrated deterrence ”. In Singapore, he said the US was working with Taiwan to enhance its capabilities to deter threats and coercion. To China, this is about as “in your face” as you can get. It is essentially throwing down the gauntlet. China is bound to respond in like manner. What makes the situation ever more dangerous is that the stronger China’s military becomes, the more Beijing thinks the US won’t fight. This is feeding China’s ever tougher response to what it considers US military provocations. Just as worrying is Allison’s conclusion that a hegemonic power like the US is likely to become more confrontational and violent as it struggles to retain dominance. If US-China relation s have not yet crossed the Rubicon, they are rapidly approaching it. Mark J. Valencia is an adjunct senior scholar at the National Institute for South China Sea Studies, Haikou, China