This is a genuinely contested question where reasonable, well-informed people disagree. Let me lay out the substance rather than a bland "it's complicated."
Where friction is real:
•Taiwan/South China Sea: China's territorial claims and military posturing directly clash with US commitments and freedom-of-navigation interests
•Technology competition: semiconductors, AI, quantum computing — both countries treat these as zero-sum for security reasons
•Economic practices: IP theft, forced tech transfer, subsidized overcapacity in industries like EVs and steel have hurt specific US sectors and workers
•Cyber espionage and influence operations
•Human rights issues (Xinjiang, Hong Kong) that clash with US values-based foreign policy
Where the "threat" framing gets overstated or is contested:
•Economic interdependence cuts both ways — a lot of US business interests benefit from China trade/investment, complicating a pure "threat" narrative
•Some China hawks in DC have incentives (budget, political) to inflate threat perception
•China's primary strategic goals (regional influence, regime security, economic growth) aren't identical to seeking confrontation with the US — Beijing has its own reasons to avoid war
•Framing China as a monolithic "threat" can obscure that US-China relations involve competition, cooperation (climate, some economic ties), and rivalry simultaneously
My honest take: China is a serious strategic competitor whose interests genuinely conflict with US interests in specific, consequential ways (Taiwan being the sharpest). Calling it an existential "threat" akin to a Cold War enemy oversimplifies a relationship that's more entangled and multidimensional than that. Whether you weight it as primarily "threat" or "competitor" often tracks with prior political leanings on China hawkishness, defense spending, and globalization more broadly.
What's the context for your question — are you thinking about a specific domain (military, economic, tech)?