On what basis did the Trisolarans conclude that humans were warlike?

Question

After receiving a radio transmission from Earth, the operator of a Trisolaran listening station chooses to send a warning against further transmissions. Summoned to explain himself, he says:

We cannot share the Earth with the people of that world. We could only destroy Earth civilization and completely take over that solar system... am I right?

The supreme leader of the Trisolarans replies:

Yes. But there is another reason for destroying Earth civilization. They're also a warlike race. Very dangerous. If we try to coexist with them on the same planet, they will shortly learn our technology.

Given the late history of the human race, this seems a reasonable conclusion. However, at that point the only information the Trisolarans had about human civilization was the contents of the radio message that had been received. This was extremely brief, no more than a short paragraph, and expressed extremely broad intentions of an idealistic nature.

On what basis did the leader conclude that humans were warlike? Was he simply extrapolating from Trisolarans?

Answer 1

Assuming the fourth draft of the official communique was broadcast without further changes ("The content of the transmission remained the same as usual"), we basically told them that we were warlike.

"But our world is still flawed. Hate exists, as does prejudice and war. Because of conflicts between the forces of production and the relations of production, wealth distribution is extremely uneven, and large portions of humanity live in poverty and misery."

Note that the paragraph we see Listener 1379 reading is only the last paragraph of a much longer communication (which we know that they received in full because the message also contained the decoding matrix). The text of the communique is found earlier in the book.