Thucydides Trap means that a newly rising power is bound to challenge the existing powers, and the existing powers will inevitably respond to this threat, so that war becomes inevitable.

This concept comes from the famous saying of Thucydides, a famous ancient Greek historian, "The real reason for the inevitability of war is the growth of Athenian power and the fear of Sparta". (Chapter 1 of the History of the Peloponnesian War) That is, in reality, the fatal combination of strategic judgment and emotional likes and dislikes of the two great powers will lead to healthy competition becoming life-and-death hostility or even worse with the passage of time.